[PATCH 1/4] serial: mxs-auart: use mctrl_gpio helpers for handling modem signals (v2.2c)
Janusz Użycki
j.uzycki at elproma.com.pl
Tue Sep 23 09:18:33 PDT 2014
Please for comments in order to resend clean patches.
4/4: can be applied separately
TODO:
- tx_empty fix
- port.lock
- pm support
best regards
Janusz
W dniu 2014-09-19 20:13, Janusz Uzycki pisze:
> Dedicated CTS and RTS pins are unusable together with a lot of other
> peripherals because they share the same line. Pinctrl is limited.
>
> Moreover, the AUART controller doesn't handle DTR/DSR/DCD/RI signals,
> so we have to control them via GPIO.
>
> This patch permits to use GPIOs to control the CTS/RTS/DTR/DSR/DCD/RI
> signals.
>
> Signed-off-by: Janusz Uzycki <j.uzycki at elproma.com.pl>
> ---
> .../devicetree/bindings/serial/fsl-mxs-auart.txt | 10 ++-
> drivers/tty/serial/Kconfig | 1 +
> drivers/tty/serial/mxs-auart.c | 77 +++++++++++++++++++++-
> 3 files changed, 84 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/serial/fsl-mxs-auart.txt
> index 59a40f1..7c408c8 100644
> --- a/Documentation/devicetree/bindings/serial/fsl-mxs-auart.txt
> +++ b/Documentation/devicetree/bindings/serial/fsl-mxs-auart.txt
> @@ -11,8 +11,13 @@ Required properties:
> - dma-names: "rx" for RX channel, "tx" for TX channel.
>
> Optional properties:
> -- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines,
> +- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines
> + for hardware flow control,
> it also means you enable the DMA support for this UART.
> +- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD
> + line respectively. It will use specified PIO instead of the peripheral
> + function pin for the USART feature.
> + If unsure, don't specify this property.
>
> Example:
> auart0: serial at 8006a000 {
> @@ -21,6 +26,9 @@ auart0: serial at 8006a000 {
> interrupts = <112>;
> dmas = <&dma_apbx 8>, <&dma_apbx 9>;
> dma-names = "rx", "tx";
> + cts-gpios = <&gpio1 15 GPIO_ACTIVE_LOW>;
> + dsr-gpios = <&gpio1 16 GPIO_ACTIVE_LOW>;
> + dcd-gpios = <&gpio1 17 GPIO_ACTIVE_LOW>;
> };
>
> Note: Each auart port should have an alias correctly numbered in "aliases"
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 4fe8ca1..90e8516 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -1357,6 +1357,7 @@ config SERIAL_MXS_AUART
> depends on ARCH_MXS
> tristate "MXS AUART support"
> select SERIAL_CORE
> + select SERIAL_MCTRL_GPIO if GPIOLIB
> help
> This driver supports the MXS Application UART (AUART) port.
>
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index 52d14e3..4690200 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -38,6 +38,9 @@
>
> #include <asm/cacheflush.h>
>
> +#include <linux/err.h>
> +#include "serial_mctrl_gpio.h"
> +
> #define MXS_AUART_MAJOR 242
> #define MXS_AUART_PORTS 5
> #define MXS_AUART_FIFO_SIZE 16
> @@ -156,6 +159,8 @@ struct mxs_auart_port {
> struct scatterlist rx_sgl;
> struct dma_chan *rx_dma_chan;
> void *rx_dma_buf;
> +
> + struct mctrl_gpios *gpios;
> };
>
> static struct platform_device_id mxs_auart_devtype[] = {
> @@ -415,8 +420,43 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)
> ctrl |= AUART_CTRL2_RTS;
> }
>
> + /* Does tty layer modify mctrl for input lines
> + * and the code below is required? */
> +#if 0
> s->ctrl = mctrl;
> +#else
> + s->ctrl &= ~(TIOCM_RTS | TIOCM_DTR);
> + s->ctrl |= mctrl & (TIOCM_RTS | TIOCM_DTR);
> +#endif
> writel(ctrl, u->membase + AUART_CTRL2);
> +
> + mctrl_gpio_set(s->gpios, mctrl);
> +}
> +
> +/* mxs_auart_modem_status() based on 8250.c,
> + * similar function could be as serial's helper... */
> +#define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
> +static u32 mxs_auart_modem_status(struct mxs_auart_port *s, u32 mctrl)
> +{
> + u32 mctrl_diff;
> +
> + mctrl_diff = mctrl ^ s->ctrl;
> + s->ctrl = mctrl;
> + if (mctrl_diff & MCTRL_ANY_DELTA &&
> + /*interrupt_enabled &&*/
> + s->port.state != NULL) {
> + if (mctrl_diff & TIOCM_RI)
> + s->port.icount.rng++;
> + if (mctrl_diff & TIOCM_DSR)
> + s->port.icount.dsr++;
> + if (mctrl_diff & TIOCM_CD)
> + uart_handle_dcd_change(&s->port, mctrl & TIOCM_CD);
> + if (mctrl_diff & TIOCM_CTS)
> + uart_handle_cts_change(&s->port, mctrl & TIOCM_CTS);
> +
> + wake_up_interruptible(&s->port.state->port.delta_msr_wait);
> + }
> + return mctrl;
> }
>
> static u32 mxs_auart_get_mctrl(struct uart_port *u)
> @@ -433,7 +473,9 @@ static u32 mxs_auart_get_mctrl(struct uart_port *u)
> if (ctrl2 & AUART_CTRL2_RTS)
> mctrl |= TIOCM_RTS;
>
> - return mctrl;
> + /* should mxs_auart_modem_status() be in interrupt only? */
> + return mxs_auart_modem_status(s,
> + mctrl_gpio_get(s->gpios, &mctrl));
> }
>
> static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s);
> @@ -637,7 +679,12 @@ static void mxs_auart_settermios(struct uart_port *u,
> ctrl |= AUART_LINECTRL_STP2;
>
> /* figure out the hardware flow control settings */
> - if (cflag & CRTSCTS) {
> + /*FIXME: DMA for hardware flow control only? */
> + if (cflag & CRTSCTS &&
> + (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(s->gpios,
> + UART_GPIO_RTS)) ||
> + IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(s->gpios,
> + UART_GPIO_CTS)))) {
> /*
> * The DMA has a bug(see errata:2836) in mx23.
> * So we can not implement the DMA for auart in mx23,
> @@ -696,8 +743,14 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
> | AUART_INTR_CTSMIS),
> s->port.membase + AUART_INTR_CLR);
>
> + mxs_auart_modem_status(s,
> + mctrl_gpio_get(s->gpios, &s->ctrl));
> +
> if (istat & AUART_INTR_CTSMIS) {
> - uart_handle_cts_change(&s->port, stat & AUART_STAT_CTS);
> + if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(s->gpios,
> + UART_GPIO_CTS)))
> + uart_handle_cts_change(&s->port,
> + stat & AUART_STAT_CTS);
> writel(AUART_INTR_CTSMIS,
> s->port.membase + AUART_INTR_CLR);
> istat &= ~AUART_INTR_CTSMIS;
> @@ -758,6 +811,8 @@ static int mxs_auart_startup(struct uart_port *u)
> */
> writel(AUART_LINECTRL_FEN, u->membase + AUART_LINECTRL_SET);
>
> + /* get initial status of modem lines */
> + mctrl_gpio_get(s->gpios, &s->ctrl);
> return 0;
> }
>
> @@ -1021,6 +1076,14 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
> return 0;
> }
>
> +static int mxs_auart_init_gpios(struct mxs_auart_port *s, struct device *dev)
> +{
> + s->gpios = mctrl_gpio_init(dev, 0);
> + if (IS_ERR_OR_NULL(s->gpios))
> + return -1;
> + return 0;
> +}
> +
> static int mxs_auart_probe(struct platform_device *pdev)
> {
> const struct of_device_id *of_id =
> @@ -1078,6 +1141,11 @@ static int mxs_auart_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, s);
>
> + ret = mxs_auart_init_gpios(s, &pdev->dev);
> + if (ret < 0)
> + dev_err(&pdev->dev, "%s",
> + "Failed to initialize GPIOs. The serial port may not work as expected");
> +
> auart_port[s->port.line] = s;
>
> mxs_auart_reset(&s->port);
> @@ -1094,6 +1162,7 @@ static int mxs_auart_probe(struct platform_device *pdev)
> return 0;
>
> out_free_irq:
> + mctrl_gpio_free(&pdev->dev, s->gpios); /*useless?*/
> auart_port[pdev->id] = NULL;
> free_irq(s->irq, s);
> out_free_clk:
> @@ -1112,6 +1181,8 @@ static int mxs_auart_remove(struct platform_device *pdev)
>
> auart_port[pdev->id] = NULL;
>
> + mctrl_gpio_free(&pdev->dev, s->gpios); /*useless?*/
> +
> clk_put(s->clk);
> free_irq(s->irq, s);
> kfree(s);
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