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drivers: lpuart: enable loopback mode

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NXP LPUART IP supports loopback mode, where TX is internally connected
to RX input. Allow setting loopback mode up via the "nxp,loopback" dts
property.

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>
This commit is contained in:
Daniel DeGrasse 2022-04-19 18:18:07 -05:00 • committed by Carles Cufí
commit 557a0c766c
2 changed files with 15 additions and 0 deletions
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8
drivers/serial/uart_mcux_lpuart.c
View file

@ -42,6 +42,7 @@ struct mcux_lpuart_config {
clock_control_subsys_t clock_subsys; clock_control_subsys_t clock_subsys;
uint32_t baud_rate; uint32_t baud_rate;
uint8_t flow_ctrl; uint8_t flow_ctrl;
bool loopback_en;
#ifdef CONFIG_UART_MCUX_LPUART_ISR_SUPPORT #ifdef CONFIG_UART_MCUX_LPUART_ISR_SUPPORT
void (*irq_config_func)(const struct device *dev); void (*irq_config_func)(const struct device *dev);
#endif #endif
@ -962,6 +963,12 @@ static int mcux_lpuart_configure_init(const struct device *dev, const struct uar
LPUART_Init(config->base, &uart_config, clock_freq); LPUART_Init(config->base, &uart_config, clock_freq);
if (config->loopback_en) {
/* Set the LPUART into loopback mode */
config->base->CTRL |= LPUART_CTRL_LOOPS_MASK;
config->base->CTRL &= ~LPUART_CTRL_RSRC_MASK;
}
/* update internal uart_config */ /* update internal uart_config */
data->uart_config = *cfg; data->uart_config = *cfg;
@ -1159,6 +1166,7 @@ static const struct mcux_lpuart_config mcux_lpuart_##n##_config = { \
.baud_rate = DT_INST_PROP(n, current_speed), \ .baud_rate = DT_INST_PROP(n, current_speed), \
.flow_ctrl = DT_INST_PROP(n, hw_flow_control) ? \ .flow_ctrl = DT_INST_PROP(n, hw_flow_control) ? \
UART_CFG_FLOW_CTRL_RTS_CTS : UART_CFG_FLOW_CTRL_NONE, \ UART_CFG_FLOW_CTRL_RTS_CTS : UART_CFG_FLOW_CTRL_NONE, \
.loopback_en = DT_INST_PROP(n, nxp_loopback), \
PINCTRL_INIT(n) \ PINCTRL_INIT(n) \
MCUX_LPUART_IRQ_INIT(n) \ MCUX_LPUART_IRQ_INIT(n) \
RX_DMA_CONFIG(n) \ RX_DMA_CONFIG(n) \

7
dts/bindings/serial/nxp,kinetis-lpuart.yaml
View file

@ -10,3 +10,10 @@ properties:
interrupts: interrupts:
required: true required: true
nxp,loopback:
type: boolean
description: |
Enable loopback mode on LPUART peripheral. When present, RX pin is
disconnected, and transmitter output is internally connected to
the receiver input.