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Merged in kekiefer/nuttx/stm32f7-serial-fix-tiocssinglewire-upstream (pull request #658)

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stm32f7: serial: Fix ioctl TIOCSSINGLEWIRE

The TRM notes that UE must be disabled in order to write HDSEL in
USART_CR3. This was not being done, so calls to TIOCSSINGLEWIRE were
silently failing.

This change checks the state of UE in USART_CR1, clears the UE bit
before writing HDSEL, then re-enables it if neccesary.

Approved-by: GregoryN <gnutt@nuttx.org>
This commit is contained in:
Kurt Kiefer 2018-06-14 13:27:07 +00:00 committed by GregoryN
parent a7a258e05e
commit ba1f8e5474
1 changed files with 21 additions and 0 deletions
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21
arch/arm/src/stm32f7/stm32_serial.c
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@ -1926,6 +1926,22 @@ static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
#ifdef CONFIG_STM32F7_USART_SINGLEWIRE
case TIOCSSINGLEWIRE:
{
uint32_t cr1;
uint32_t cr1_ue;
irqstate_t flags;
flags = enter_critical_section();
/* Get the original state of UE */
cr1 = up_serialin(priv, STM32_USART_CR1_OFFSET);
cr1_ue = cr1 & USART_CR1_UE;
cr1 &= ~USART_CR1_UE;
/* Disable UE, HDSEL can only be written when UE=0 */
up_serialout(priv, STM32_USART_CR1_OFFSET, cr1);
/* Change the TX port to be open-drain/push-pull and enable/disable
* half-duplex mode.
*/
@ -1944,6 +1960,11 @@ static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
}
up_serialout(priv, STM32_USART_CR3_OFFSET, cr);
/* Re-enable UE if appropriate */
up_serialout(priv, STM32_USART_CR1_OFFSET, cr1 | cr1_ue);
leave_critical_section(flags);
}
break;
#endif