/**************************************************************************** * drivers/lcd/pcf8574_lcd_backpack.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include #include #ifndef CONFIG_LIBC_SLCDCODEC # error please also select Library Routines, Segment LCD CODEC #endif /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* The PCF8574 is a 100 KHz device */ #define I2C_FREQ 100000 /* timing characteristics of the LCD interface */ #define DELAY_US_NYBBLE0 20 #define DELAY_US_NYBBLE1 10 #define DELAY_US_WRITE 40 #define DELAY_US_HOMECLEAR 2000 /* HD44780 commands */ #define CMD_CLEAR 0x01 #define CMD_HOME 0x02 #define CMD_CURSOR_ON_SOLID 0x0e #define CMD_CURSOR_OFF 0x0c #define CMD_CURSOR_ON_BLINK 0x0f #define CMD_SET_CGADDR 0x40 #define CMD_SET_DDADDR 0x80 #define MAX_OPENCNT (255) /* Limit of uint8_t */ /**************************************************************************** * Private Types ****************************************************************************/ struct pcf8574_lcd_dev_s { FAR struct i2c_master_s *i2c; /* I2C interface */ struct pcf8574_lcd_backpack_config_s cfg; /* gpio configuration */ uint8_t bl_bit; /* current backlight bit */ uint8_t refs; /* Number of references */ uint8_t unlinked; /* We are unlinked, so teardown * on last close */ mutex_t lock; /* mutex */ }; /**************************************************************************** * Private Function Prototypes ****************************************************************************/ /* Character driver methods */ static int pcf8574_lcd_open(FAR struct file *filep); static int pcf8574_lcd_close(FAR struct file *filep); static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer, size_t buflen); static ssize_t pcf8574_lcd_write(FAR struct file *filep, FAR const char *buffer, size_t buflen); static off_t pcf8574_lcd_seek(FAR struct file *filep, off_t offset, int whence); static int pcf8574_lcd_ioctl(FAR struct file *filep, int cmd, unsigned long arg); static int pcf8574_lcd_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup); #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int pcf8574_lcd_unlink(FAR struct inode *inode); #endif /**************************************************************************** * Private Data ****************************************************************************/ static const struct file_operations g_pcf8574_lcd_fops = { pcf8574_lcd_open, /* open */ pcf8574_lcd_close, /* close */ pcf8574_lcd_read, /* read */ pcf8574_lcd_write, /* write */ pcf8574_lcd_seek, /* seek */ pcf8574_lcd_ioctl, /* ioctl */ NULL, /* mmap */ NULL, /* truncate */ pcf8574_lcd_poll /* poll */ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS , pcf8574_lcd_unlink /* unlink */ #endif }; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: pca8574_write * * Description: * primitive I2C write operation for the PCA8574, which is the IO expander * device used on the board. The board essentially byte-bangs the * parallel interface in nybble mode much as one might with a conventional * GPIO based interface. The I2C interface simply sets the state of the * 8 IO lines to control the 4 data, 3 control, and one for backlight, * signals. * ****************************************************************************/ static void pca8574_write(FAR struct pcf8574_lcd_dev_s *priv, uint8_t data) { struct i2c_config_s config; int ret; /* Set up the I2C configuration */ config.frequency = I2C_FREQ; config.address = priv->cfg.addr; config.addrlen = 7; /* Write the value */ ret = i2c_write(priv->i2c, &config, &data, 1); if (ret < 0) { lcdinfo("pca8574_write() failed: %d\n", ret); return; } } /**************************************************************************** * Name: pca8574_read * * Description: * primitive I2C read operation for the PCA8574, which is the IO expander * device used on the board. The PCF8574 is 'interesting' in that it * doesn't really have a data direction register, but instead the outputs * are current-limited when high, so by setting an IO line high, you are * also making it an input. Consequently, before using this method, you'll * need to perform a pca8574_write() setting the bits you are interested in * reading to 1's, then call this method. * ****************************************************************************/ static int pca8574_read(FAR struct pcf8574_lcd_dev_s *priv, uint8_t *data) { struct i2c_config_s config; int ret; /* Set up the I2C configuration */ config.frequency = I2C_FREQ; config.address = priv->cfg.addr; config.addrlen = 7; /* Read the value */ ret = i2c_read(priv->i2c, &config, data, 1); if (ret < 0) { lcdinfo("pca8574_read() failed: %d\n", ret); } return ret; } /**************************************************************************** * Name: lcd_backlight * * Description: * turn on, or off, the LCD backlight * ****************************************************************************/ static void lcd_backlight(FAR struct pcf8574_lcd_dev_s *priv, bool blon) { uint8_t data; data = ((blon && priv->cfg.bl_active_high) || (!blon && !priv->cfg.bl_active_high)) ? (1 << priv->cfg.bl) : 0; pca8574_write(priv, data); priv->bl_bit = data; } /**************************************************************************** * Name: rc2addr * * Description: * This converts a row/column pair to a screen memory address. * ****************************************************************************/ static inline uint8_t rc2addr(FAR struct pcf8574_lcd_dev_s *priv, uint8_t row, uint8_t col) { if (row < 2) { /* 1 and 2 line displays are simple; line0 @ 0x00, line1 @ 0x40 */ return row * 0x40 + col; } else { /* 4 line displays are interesting; third line really is a continuation * of first line, and fourth line is a continuation of second. */ return (row - 2) * 0x40 + (col + priv->cfg.cols); } } /**************************************************************************** * Name: addr2rc * * Description: * This converts a screen memory address to a row/column pair. * ****************************************************************************/ static inline void addr2rc(FAR struct pcf8574_lcd_dev_s *priv, uint8_t addr, FAR uint8_t *row, FAR uint8_t *col) { *row = addr / 0x40; *col = addr % 0x40; if (*col >= priv->cfg.cols) { /* 4 line displays have third and fourth lines really as continuation * of the first and second. */ *row += 2; *col -= priv->cfg.cols; } } /**************************************************************************** * Name: prepare_nybble * * Description: * This is a bit tedious, but scramble the bits of the nybble into position * as per this board's particular wiring. Most boards are either on the * top four bits, or bottom four, so a shift would do typically in those * cases, but this gives us ultimate flexibility. * ****************************************************************************/ uint8_t prepare_nybble(FAR struct pcf8574_lcd_dev_s *priv, uint8_t nybble) { uint8_t lcddata = 0; if (nybble & 0x08) { lcddata |= (1 << priv->cfg.d7); } if (nybble & 0x04) { lcddata |= (1 << priv->cfg.d6); } if (nybble & 0x02) { lcddata |= (1 << priv->cfg.d5); } if (nybble & 0x01) { lcddata |= (1 << priv->cfg.d4); } return lcddata; } /**************************************************************************** * Name: unprepare_nybble * * Description: * This is the opposite of prepare_nybble(), and is used to unscramble bits * when reading data from the display, as per board wiring. * ****************************************************************************/ uint8_t unprepare_nybble(FAR struct pcf8574_lcd_dev_s *priv, uint8_t lcddata) { uint8_t data = 0; if (lcddata & (1 << priv->cfg.d7)) { data |= 0x08; } if (lcddata & (1 << priv->cfg.d6)) { data |= 0x04; } if (lcddata & (1 << priv->cfg.d5)) { data |= 0x02; } if (lcddata & (1 << priv->cfg.d4)) { data |= 0x01; } return data; } /**************************************************************************** * Name: latch_nybble * * Description: * Latch a nybble on the LCD bus. This is done for each of two halves of a * write operation in 4-bit mode. The 'rs' param is false for command * transfers, and true for data transfers. * ****************************************************************************/ static void latch_nybble(FAR struct pcf8574_lcd_dev_s *priv, uint8_t nybble, bool rs) { uint8_t lcddata; uint8_t en_bit; uint8_t rs_bit; en_bit = 1 << priv->cfg.en; rs_bit = rs ? (1 << priv->cfg.rs) : 0; /* Put the nybble, preserving backlight, reset R/~W and maybe RS */ lcddata = prepare_nybble(priv, nybble) | priv->bl_bit | rs_bit; pca8574_write(priv, lcddata); /* Now set EN */ lcddata |= en_bit; pca8574_write(priv, lcddata); up_udelay(DELAY_US_NYBBLE0); /* setup */ /* Latch on EN falling edge */ lcddata &= ~en_bit; pca8574_write(priv, lcddata); up_udelay(DELAY_US_NYBBLE1); /* hold */ } /**************************************************************************** * Name: load_nybble * * Description: * Load a nybble from the LCD bus. This is done for each of two halves of a * read operation in 4-bit mode. The 'rs' param is false for command * transfers (the only one is to read status and the address register), and * true for data transfers. * ****************************************************************************/ static uint8_t load_nybble(FAR struct pcf8574_lcd_dev_s *priv, bool rs) { uint8_t lcddata; uint8_t en_bit; uint8_t rs_bit; uint8_t rw_bit; uint8_t data; en_bit = 1 << priv->cfg.en; rs_bit = rs ? (1 << priv->cfg.rs) : 0; rw_bit = 1 << priv->cfg.rw; /* Put highs on the data lines, preserve, set R/~W and maybe RS */ lcddata = prepare_nybble(priv, 0x0f) | priv->bl_bit | rw_bit | rs_bit; pca8574_write(priv, lcddata); /* Now set EN */ lcddata |= en_bit; pca8574_write(priv, lcddata); up_udelay(DELAY_US_NYBBLE0); /* setup */ /* Now read the data */ pca8574_read(priv, &data); data = unprepare_nybble(priv, data); /* Transaction completed on EN falling edge */ lcddata &= ~en_bit; pca8574_write(priv, lcddata); up_udelay(DELAY_US_NYBBLE1); /* hold */ return data; } /**************************************************************************** * Name: lcd_putcmd * * Description: * Write a command to the LCD. Most of the time this is done in nybble * mode in two phases, but in special cases (like initialization) we do not * do two phases. * ****************************************************************************/ static void lcd_putcmd(FAR struct pcf8574_lcd_dev_s *priv, uint8_t data) { latch_nybble(priv, data >> 4, false); latch_nybble(priv, data, false); up_udelay(DELAY_US_WRITE); } /**************************************************************************** * Name: lcd_putdata * * Description: * Write a byte to the LCD. This is used both for screen data and for * character generator data, depending on a previous command that selected * which ever is the destination. * ****************************************************************************/ static inline void lcd_putdata(FAR struct pcf8574_lcd_dev_s *priv, uint8_t data) { latch_nybble(priv, data >> 4, true); latch_nybble(priv, data, true); up_udelay(DELAY_US_WRITE); } /**************************************************************************** * Name: lcd_getdata * * Description: * Read a data byte from the LCD. * ****************************************************************************/ static inline uint8_t lcd_getdata(FAR struct pcf8574_lcd_dev_s *priv) { uint8_t data; data = (load_nybble(priv, true) << 4) | load_nybble(priv, true); return data; } /**************************************************************************** * Name: lcd_getcmd * * Description: * Read a command byte from the LCD. There really is only one such read: * get 'busy' status, and current address value. * ****************************************************************************/ static inline uint8_t lcd_getcmd(FAR struct pcf8574_lcd_dev_s *priv) { uint8_t data; data = (load_nybble(priv, false) << 4) | load_nybble(priv, false); return data; } /**************************************************************************** * Name: lcd_read_busy_addr * * Description: * Read the busy flag, and, optionally, the current value of the address * register (data or character generator dependent on a previous command). * ****************************************************************************/ static bool lcd_read_busy_addr(FAR struct pcf8574_lcd_dev_s *priv, FAR uint8_t *addr) { uint8_t data = lcd_getcmd(priv); if (NULL != addr) { *addr = data & 0x7f; } return (data & 0x80) ? true : false; } /**************************************************************************** * Name: lcd_init * * Description: * perform the initialization sequence to get the LCD into a known state. * ****************************************************************************/ static void lcd_init(FAR struct pcf8574_lcd_dev_s *priv) { /* Wait for more than 15 ms after Vcc for the LCD to stabilize */ nxsig_usleep(50000); /* Perform the init sequence. This sequence of commands is constructed so * that it will get the device into nybble mode irrespective of what state * the device is currently in (could be 8 bit, 4 bit nyb 0, 4 bit nyb 1). * By sending the 'set 8-bit mode' three times, we will definitely end up * in 8 bit mode, and then we can reliably transition to 4 bit mode for * the remainder of operations. */ /* Send Command 0x30, set 8-bit mode, and wait > 4.1 ms */ latch_nybble(priv, 0x30 >> 4, false); nxsig_usleep(5000); /* Send Command 0x30, set 8-bit mode, and wait > 100 us */ latch_nybble(priv, 0x30 >> 4, false); nxsig_usleep(5000); /* Send Command 0x30, set 8-bit mode */ latch_nybble(priv, 0x30 >> 4, false); nxsig_usleep(200); /* now Function set: Set interface to be 4 bits long (only 1 cycle write * for the first time). */ latch_nybble(priv, 0x20 >> 4, false); nxsig_usleep(5000); /* Function set: DL=0;Interface is 4 bits, N=1 (2 Lines), F=0 (5x8 dots * font) */ lcd_putcmd(priv, 0x28); /* Display Off: D=0 (Display off), C=0 (Cursor Off), B=0 (Blinking Off) */ lcd_putcmd(priv, 0x08); /* Display Clear */ lcd_putcmd(priv, CMD_CLEAR); up_udelay(DELAY_US_HOMECLEAR); /* clear needs extra time */ /* Entry Mode Set: I/D=1 (Increment), S=0 (No shift) */ lcd_putcmd(priv, 0x06); /* Display On, Cursor Off */ lcd_putcmd(priv, 0x0c); } /**************************************************************************** * Name: lcd_create_char * * Description: * This creates a custom character pattern. There can be 8 5x8 patterns. * The bitmap proceeds top to bottom, msb-lsb, and is right justified (i.e. * only bits 4-0 are used). By convention, you are meant to always leave * the last line (byte) zero so that the cursor can use this line, but this * is not strictly required. * * Input Parameters: * priv - device instance * idxchar - which character is being imaged; 0 - 7 * chardata - the character image bitmap; must be 8 bytes always * ****************************************************************************/ static void lcd_create_char(FAR struct pcf8574_lcd_dev_s *priv, uint8_t idxchar, FAR const uint8_t *chardata) { int nidx; uint8_t addr; lcd_read_busy_addr(priv, &addr); lcd_putcmd(priv, CMD_SET_CGADDR | (idxchar << 3)); /* set CGRAM address */ for (nidx = 0; nidx < 8; ++nidx) { lcd_putdata(priv, chardata[nidx]); } lcd_putcmd(priv, CMD_SET_DDADDR | addr); /* restore DDRAM address */ } /**************************************************************************** * Name: lcd_set_curpos * * Description: * This sets the cursor position based on row, column addressing. * * Input Parameters: * priv - device instance * row - row position * col - column position * ****************************************************************************/ static void lcd_set_curpos(FAR struct pcf8574_lcd_dev_s *priv, uint8_t row, uint8_t col) { uint8_t addr; addr = rc2addr(priv, row, col); lcd_putcmd(priv, CMD_SET_DDADDR | addr); /* set DDRAM address */ } /**************************************************************************** * Name: lcd_get_curpos * * Description: * This gets the cursor position based on row, column addressing. * * Input Parameters: * priv - device instance * row - row position * col - column position * ****************************************************************************/ static void lcd_get_curpos(FAR struct pcf8574_lcd_dev_s *priv, FAR uint8_t *row, FAR uint8_t *col) { uint8_t addr; lcd_read_busy_addr(priv, &addr); addr2rc(priv, addr, row, col); } /**************************************************************************** * Name: lcd_scroll_up * * Description: * Scroll the display up, and clear the new (last) line. * ****************************************************************************/ static void lcd_scroll_up(FAR struct pcf8574_lcd_dev_s *priv) { FAR uint8_t *data; int nrow; int ncol; data = kmm_malloc(priv->cfg.cols); if (NULL == data) { lcdinfo("Failed to allocate buffer in lcd_scroll_up()\n"); return; } for (nrow = 1; nrow < priv->cfg.rows; ++nrow) { lcd_set_curpos(priv, nrow, 0); for (ncol = 0; ncol < priv->cfg.cols; ++ncol) { data[ncol] = lcd_getdata(priv); } lcd_set_curpos(priv, nrow - 1, 0); for (ncol = 0; ncol < priv->cfg.cols; ++ncol) { lcd_putdata(priv, data[ncol]); } } lcd_set_curpos(priv, priv->cfg.rows - 1, 0); for (ncol = 0; ncol < priv->cfg.cols; ++ncol) { lcd_putdata(priv, ' '); } lcd_set_curpos(priv, priv->cfg.rows - 1, 0); kmm_free(data); } /**************************************************************************** * Name: lcd_codec_action * * Description: * Perform an 'action' as per the Segment LCD codec. * * Input Parameters: * priv - device instance * code - SLCD code action code * count - count param for those actions that take it * ****************************************************************************/ static void lcd_codec_action(FAR struct pcf8574_lcd_dev_s *priv, enum slcdcode_e code, uint8_t count) { switch (code) { /* Erasure */ case SLCDCODE_BACKDEL: /* Backspace (backward delete) N characters */ { if (count <= 0) /* silly case */ { break; } else { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); if (count > col) /* saturate to preceding columns available */ { count = col; } lcd_set_curpos(priv, row, col - count); } /* ... and conscientiously fall through to next case ... */ } case SLCDCODE_FWDDEL: /* Delete (forward delete) N characters, moving text */ { if (count <= 0) /* silly case */ { break; } else { uint8_t row; uint8_t col; uint8_t start; uint8_t end; uint8_t nidx; uint8_t data; lcd_get_curpos(priv, &row, &col); start = col + count; if (start >= priv->cfg.cols) /* silly case of nothing left */ { break; } end = start + count; if (end > priv->cfg.cols) /* saturate */ { end = priv->cfg.cols; } for (nidx = col; nidx < end; ++start, ++nidx) /* much like memmove */ { lcd_set_curpos(priv, row, start); data = lcd_getdata(priv); lcd_set_curpos(priv, row, nidx); lcd_putdata(priv, data); } for (; nidx < priv->cfg.cols; ++nidx) /* much like memset */ { lcd_putdata(priv, ' '); } lcd_set_curpos(priv, row, col); } } break; case SLCDCODE_ERASE: /* Erase N characters from the cursor position */ if (count > 0) { uint8_t row; uint8_t col; uint8_t end; uint8_t nidx; lcd_get_curpos(priv, &row, &col); end = col + count; if (end > priv->cfg.cols) { end = priv->cfg.cols; } for (nidx = col; nidx < end; ++nidx) { lcd_putdata(priv, ' '); } lcd_set_curpos(priv, row, col); } break; case SLCDCODE_CLEAR: /* Home the cursor and erase the entire display */ { lcd_putcmd(priv, CMD_CLEAR); up_udelay(DELAY_US_HOMECLEAR); /* clear needs extra time */ } break; case SLCDCODE_ERASEEOL: /* Erase from the cursor position to the end of * line */ { uint8_t row; uint8_t col; uint8_t nidx; lcd_get_curpos(priv, &row, &col); for (nidx = col; nidx < priv->cfg.cols; ++nidx) { lcd_putdata(priv, ' '); } lcd_set_curpos(priv, row, col); } break; /* Cursor movement */ case SLCDCODE_LEFT: /* Cursor left by N characters */ { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); if (count > col) { col = 0; } else { col -= count; } lcd_set_curpos(priv, row, col); } break; case SLCDCODE_RIGHT: /* Cursor right by N characters */ { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); col += count; if (col >= priv->cfg.cols) { col = priv->cfg.cols - 1; } lcd_set_curpos(priv, row, col); } break; case SLCDCODE_UP: /* Cursor up by N lines */ { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); if (count > row) { row = 0; } else { row -= count; } lcd_set_curpos(priv, row, col); } break; case SLCDCODE_DOWN: /* Cursor down by N lines */ { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); row += count; if (row >= priv->cfg.rows) { row = priv->cfg.rows - 1; } lcd_set_curpos(priv, row, col); } break; case SLCDCODE_HOME: /* Cursor home */ { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); lcd_set_curpos(priv, row, 0); } break; case SLCDCODE_END: /* Cursor end */ { uint8_t row; uint8_t col; lcd_get_curpos(priv, &row, &col); lcd_set_curpos(priv, row, priv->cfg.cols - 1); } break; case SLCDCODE_PAGEUP: /* Cursor up by N pages */ case SLCDCODE_PAGEDOWN: /* Cursor down by N pages */ break; /* Not supportable on this SLCD */ /* Blinking */ case SLCDCODE_BLINKSTART: /* Start blinking with current cursor position */ lcd_putcmd(priv, CMD_CURSOR_ON_BLINK); break; case SLCDCODE_BLINKEND: /* End blinking after the current cursor * position */ case SLCDCODE_BLINKOFF: /* Turn blinking off */ lcd_putcmd(priv, CMD_CURSOR_OFF); break; /* Not implemented */ /* These are actually unreportable errors */ default: case SLCDCODE_NORMAL: /* Not a special keycode */ break; } } /**************************************************************************** * Name: lcd_fpos_to_curpos * * Description: * Convert a file logical offset to a screen cursor pos (row,col). This * discounts 'synthesized' line feeds at the end of screen lines. * ****************************************************************************/ static void lcd_fpos_to_curpos(FAR struct pcf8574_lcd_dev_s *priv, off_t fpos, FAR uint8_t *row, FAR uint8_t *col, FAR bool *onlf) { int virtcols; virtcols = (priv->cfg.cols + 1); /* Determine if this is a 'virtual' position (on the synthetic LF) */ *onlf = (priv->cfg.cols == fpos % virtcols); /* Adjust off any preceding synthetic LF's to get linear position */ fpos -= fpos / virtcols; /* Compute row/col from linear position */ *row = fpos / priv->cfg.cols; *col = fpos % priv->cfg.cols; } /**************************************************************************** * Name: lcd_curpos_to_fpos * * Description: * Convert a screen cursor pos (row,col) to a file logical offset. This * includes 'synthesized' line feeds at the end of screen lines. * ****************************************************************************/ static void lcd_curpos_to_fpos(FAR struct pcf8574_lcd_dev_s *priv, uint8_t row, uint8_t col, FAR off_t *fpos) { /* the logical file position is the linear position plus any synthetic LF */ *fpos = (row * priv->cfg.cols) + col + row; } /**************************************************************************** * Name: pcf8574_lcd_open * * Description: * requisite device 'open' method; we don't do anything special * ****************************************************************************/ static int pcf8574_lcd_open(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; /* Increment the reference count */ nxmutex_lock(&priv->lock); if (priv->refs == MAX_OPENCNT) { nxmutex_unlock(&priv->lock); return -EMFILE; } else { priv->refs++; } nxmutex_unlock(&priv->lock); return OK; } /**************************************************************************** * Name: pcf8574_lcd_close * * Description: * requisite device 'close' method; we don't do anything special * ****************************************************************************/ static int pcf8574_lcd_close(FAR struct file *filep) { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; int ret; /* Decrement the reference count */ nxmutex_lock(&priv->lock); if (priv->refs == 0) { ret = -EIO; } else { priv->refs--; /* If we had previously unlinked, but there were open references at * the time, we need to do the final teardown now. */ if (priv->refs == 0 && priv->unlinked) { /* We have no real teardown at present */ } ret = OK; } nxmutex_unlock(&priv->lock); return ret; } /**************************************************************************** * Name: pcf8574_lcd_read * * Description: * This simply reads as much of the display memory as possible. This is * generally not very interesting, but we do it in a way that allows us to * 'cat' the LCD contents via the shell. * ****************************************************************************/ static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer, size_t buflen) { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; int nidx; uint8_t addr; uint8_t row; uint8_t col; bool onlf; nxmutex_lock(&priv->lock); /* Get current cursor position so we can restore it */ lcd_read_busy_addr(priv, &addr); /* Convert file position to row/col address and position DDADDR there */ lcd_fpos_to_curpos(priv, filep->f_pos, &row, &col, &onlf); lcd_set_curpos(priv, row, col); /* Read as much of the display as possible */ nidx = 0; while (nidx < buflen && row < priv->cfg.rows) { /* Synthesize end-of-line LF and advance to start of next row */ if (onlf) { /* Synthesize LF for all but last row */ if (row < priv->cfg.rows - 1) { buffer[nidx] = '\x0a'; onlf = false; ++filep->f_pos; ++nidx; } ++row; col = 0; continue; } /* If we are at start of line we will need to update DDRAM address */ if (0 == col) { lcd_set_curpos(priv, row, 0); } buffer[nidx] = lcd_getdata(priv); ++filep->f_pos; ++nidx; ++col; /* If we are now at the end of a line, we setup for the synthetic LF */ if (priv->cfg.cols == col) { onlf = true; } } lcd_putcmd(priv, CMD_SET_DDADDR | addr); /* Restore DDRAM address */ nxmutex_unlock(&priv->lock); return nidx; } /**************************************************************************** * Name: pcf8574_lcd_write * * Description: * Output a sequence of characters to the device. * ****************************************************************************/ static ssize_t pcf8574_lcd_write(FAR struct file *filep, FAR const char *buffer, size_t buflen) { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; struct lib_meminstream_s instream; uint8_t row; uint8_t col; struct slcdstate_s state; enum slcdret_e result; uint8_t ch; uint8_t count; nxmutex_lock(&priv->lock); /* Initialize the stream for use with the SLCD CODEC */ lib_meminstream(&instream, buffer, buflen); /* Get the current cursor position now; we'll keep track of it as we go */ lcd_get_curpos(priv, &row, &col); /* Now decode and process every byte in the input buffer */ memset(&state, 0, sizeof(struct slcdstate_s)); while ((result = slcd_decode(&instream.common, &state, &ch, &count)) != SLCDRET_EOF) { if (result == SLCDRET_CHAR) /* A normal character was returned */ { /* Check for ASCII control characters */ if (ch == ASCII_TAB) { lcd_putcmd(priv, CMD_CURSOR_ON_BLINK); } else if (ch == ASCII_VT) { /* Turn the backlight on */ lcd_backlight(priv, true); } else if (ch == ASCII_FF) { /* Turn the backlight off */ lcd_backlight(priv, false); } else if (ch == ASCII_CR) { /* Perform a Home */ lcd_putcmd(priv, CMD_HOME); up_udelay(DELAY_US_HOMECLEAR); /* home needs extra time */ row = 0; col = 0; } else if (ch == ASCII_SO) { lcd_putcmd(priv, CMD_CURSOR_OFF); } else if (ch == ASCII_SI) { /* Perform the re-initialize */ lcd_init(priv); row = 0; col = 0; } else if (ch == ASCII_LF) { /* unixian line term; go to start of next line */ row += 1; if (row >= priv->cfg.rows) { lcd_scroll_up(priv); row = priv->cfg.rows - 1; } col = 0; lcd_set_curpos(priv, row, col); } else if (ch == ASCII_BS) { /* Perform the backward deletion */ lcd_codec_action(priv, SLCDCODE_BACKDEL, 1); lcd_get_curpos(priv, &row, &col); } else if (ch == ASCII_DEL) { /* Perform the forward deletion */ lcd_codec_action(priv, SLCDCODE_FWDDEL, 1); lcd_get_curpos(priv, &row, &col); } else { /* All others are fair game. See if we need to wrap line. */ if (col >= priv->cfg.cols) { row += 1; if (row >= priv->cfg.rows) { lcd_scroll_up(priv); row = priv->cfg.rows - 1; } col = 0; lcd_set_curpos(priv, row, col); } lcd_putdata(priv, ch); ++col; } } /* A special SLCD action was returned */ else /* (result == SLCDRET_SPEC) */ { lcd_codec_action(priv, (enum slcdcode_e)ch, count); /* we can't know what happened, so it's easier just to re-inquire * as to where we are. */ lcd_get_curpos(priv, &row, &col); } } /* Wherever we wound up, update our logical file pos to reflect it */ lcd_curpos_to_fpos(priv, row, col, &filep->f_pos); nxmutex_unlock(&priv->lock); return buflen; } /**************************************************************************** * Name: pcf8574_lcd_seek * * Description: * Seek the logical file pointer to the specified position. This is * probably not very interesting except possibly for (SEEK_SET, 0) to * rewind the pointer for a subsequent read(). * The file pointer is logical, and includes synthesized LF chars at the * end of the display lines. * ****************************************************************************/ static off_t pcf8574_lcd_seek(FAR struct file *filep, off_t offset, int whence) { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; off_t pos; int maxpos; nxmutex_lock(&priv->lock); maxpos = priv->cfg.rows * priv->cfg.cols + (priv->cfg.rows - 1); pos = filep->f_pos; switch (whence) { case SEEK_CUR: pos += offset; if (pos > maxpos) { pos = maxpos; } else if (pos < 0) { pos = 0; } filep->f_pos = pos; break; case SEEK_SET: pos = offset; if (pos > maxpos) { pos = maxpos; } else if (pos < 0) { pos = 0; } filep->f_pos = pos; break; case SEEK_END: pos = maxpos + offset; if (pos > maxpos) { pos = maxpos; } else if (pos < 0) { pos = 0; } filep->f_pos = pos; break; default: /* Return EINVAL if the whence argument is invalid */ pos = (off_t) - EINVAL; break; } nxmutex_unlock(&priv->lock); return pos; } /**************************************************************************** * Name: pcf8574_lcd_ioctl * * Description: * Perform device operations that are outside the standard I/O model. * ****************************************************************************/ static int pcf8574_lcd_ioctl(FAR struct file *filep, int cmd, unsigned long arg) { switch (cmd) { case SLCDIOC_GETATTRIBUTES: /* SLCDIOC_GETATTRIBUTES: Get the * attributes of the SLCD */ { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; FAR struct slcd_attributes_s *attr = (FAR struct slcd_attributes_s *)((uintptr_t) arg); lcdinfo("SLCDIOC_GETATTRIBUTES:\n"); if (!attr) { return -EINVAL; } attr->nrows = priv->cfg.rows; attr->ncolumns = priv->cfg.cols; attr->nbars = 0; attr->maxcontrast = 0; attr->maxbrightness = 1; /* 'brightness' for us is the backlight */ } break; case SLCDIOC_CURPOS: /* SLCDIOC_CURPOS: Get the SLCD cursor position */ { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; FAR struct slcd_curpos_s *attr = (FAR struct slcd_curpos_s *)((uintptr_t) arg); uint8_t row; uint8_t col; nxmutex_lock(&priv->lock); lcd_get_curpos(priv, &row, &col); attr->row = row; attr->column = col; nxmutex_unlock(&priv->lock); } break; case SLCDIOC_GETBRIGHTNESS: /* Get the current brightness setting */ { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; bool bon; bon = (priv->bl_bit && priv->cfg.bl_active_high) || (!priv->bl_bit && !priv->cfg.bl_active_high); *(FAR int *)((uintptr_t) arg) = bon ? 1 : 0; } break; case SLCDIOC_SETBRIGHTNESS: /* Set the brightness to a new value */ { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; nxmutex_lock(&priv->lock); lcd_backlight(priv, arg ? true : false); nxmutex_unlock(&priv->lock); } break; case SLCDIOC_CREATECHAR: /* Create a custom character pattern */ { FAR struct inode *inode = filep->f_inode; FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; FAR struct slcd_createchar_s *attr = (FAR struct slcd_createchar_s *)((uintptr_t) arg); nxmutex_lock(&priv->lock); lcd_create_char(priv, attr->idx, attr->bmp); nxmutex_unlock(&priv->lock); } break; case SLCDIOC_SETBAR: /* SLCDIOC_SETBAR: Set bars on a bar display */ case SLCDIOC_GETCONTRAST: /* SLCDIOC_GETCONTRAST: Get the current * contrast setting */ case SLCDIOC_SETCONTRAST: /* SLCDIOC_SETCONTRAST: Set the contrast to a * new value */ default: return -ENOTTY; } return OK; } /**************************************************************************** * Name: pcf8574_lcd_poll ****************************************************************************/ static int pcf8574_lcd_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup) { if (setup) { /* Data is always available to be read */ poll_notify(&fds, 1, POLLIN | POLLOUT); } return OK; } /**************************************************************************** * Name: pcf8574_lcd_unlink ****************************************************************************/ #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS static int pcf8574_lcd_unlink(FAR struct inode *inode) { FAR struct pcf8574_lcd_dev_s *priv = inode->i_private; int ret = OK; nxmutex_lock(&priv->lock); priv->unlinked = true; /* If there are no open references to the driver then tear it down now */ if (priv->refs == 0) { /* We have no real teardown at present */ ret = OK; } nxmutex_unlock(&priv->lock); return ret; } #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: pcf8574_lcd_backpack_register * * Description: * Register a character driver that is an I2C LCD 'backpack' for the * ever-popular HD44780 based 16x2 LCD via pcf8574 I2C IO expander. * ****************************************************************************/ int pcf8574_lcd_backpack_register(FAR const char *devpath, FAR struct i2c_master_s *i2c, FAR struct pcf8574_lcd_backpack_config_s *cfg) { FAR struct pcf8574_lcd_dev_s *priv; int ret; /* Sanity check on geometry */ if (cfg->rows < 1 || cfg->rows > 4) { lcdinfo("Display rows must be 1-4\n"); return -EINVAL; } if ((cfg->cols < 1 || cfg->cols > 64) || (cfg->rows == 4 && cfg->cols > 32)) { lcdinfo("Display cols must be 1-64, and may not be part of a 4x40 " "configuration\n"); return -EINVAL; } /* Initialize the device structure */ priv = (FAR struct pcf8574_lcd_dev_s *) kmm_malloc(sizeof(struct pcf8574_lcd_dev_s)); if (!priv) { lcdinfo("Failed to allocate instance\n"); return -ENOMEM; } priv->i2c = i2c; priv->cfg = *cfg; priv->bl_bit = priv->cfg.bl_active_high ? 0 : (1 << priv->cfg.bl); priv->refs = 0; priv->unlinked = false; nxmutex_init(&priv->lock); /* Initialize */ lcd_init(priv); /* If SLCD is console enable the backlight from start */ #ifdef CONFIG_SLCD_CONSOLE lcd_backlight(priv, true); #endif /* Register the character driver */ ret = register_driver(devpath, &g_pcf8574_lcd_fops, 0666, priv); if (ret < 0) { lcdinfo("Failed to register driver: %d\n", ret); nxmutex_destroy(&priv->lock); kmm_free(priv); } lcdinfo("pcf8574_lcd_backpack driver loaded successfully!\n"); return ret; }