Subject: [PATCH 3/4] serial: mxs-auart: add interrupts for modem control lines

From: [email-masked] (Richard Genoud)
Date: Fri, 24 Oct 2014 17:32:42 +0200

On 27/09/2014 11:46, Janusz Uzycki wrote:
> Handle CTS/DSR/RI/DCD GPIO interrupts in mxs-auart.
> 
> Signed-off-by: Janusz Uzycki <[email-masked]>
> ---
>  drivers/tty/serial/mxs-auart.c | 176 ++++++++++++++++++++++++++-
>  1 file changed, 174 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
> index fdfa8a9..ab127a2 100644
> --- a/drivers/tty/serial/mxs-auart.c
> +++ b/drivers/tty/serial/mxs-auart.c
> @@ -42,7 +42,10 @@
>  
>  #include <asm/cacheflush.h>
>  
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/err.h>
> +#include <linux/irq.h>
>  #include "serial_mctrl_gpio.h"
>  
>  #define MXS_AUART_PORTS 5
> @@ -146,6 +149,7 @@ struct mxs_auart_port {
>  #define MXS_AUART_DMA_RX_READY	3  /* bit 3 */
>  #define MXS_AUART_RTSCTS	4  /* bit 4 */
>  	unsigned long flags;
> +	unsigned int mctrl_prev;
>  	enum mxs_auart_type devtype;
>  
>  	unsigned int irq;
> @@ -163,6 +167,8 @@ struct mxs_auart_port {
>  	void *rx_dma_buf;
>  
>  	struct mctrl_gpios	*gpios;
> +	int			gpio_irq[UART_GPIO_MAX];
> +	bool			ms_irq_enabled;
>  };
>  
>  static struct platform_device_id mxs_auart_devtype[] = {
> @@ -427,6 +433,29 @@ static void mxs_auart_set_mctrl(struct uart_port *u, unsigned mctrl)
>  	mctrl_gpio_set(s->gpios, mctrl);
>  }
>  
> +#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->mctrl_prev;
> +	s->mctrl_prev = mctrl;
> +	if (mctrl_diff & MCTRL_ANY_DELTA && s->ms_irq_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)
>  {
>  	struct mxs_auart_port *s = to_auart_port(u);
> @@ -444,6 +473,64 @@ static u32 mxs_auart_get_mctrl(struct uart_port *u)
>  	return mctrl_gpio_get(s->gpios, &mctrl);
>  }
>  
> +/*
> + * Enable modem status interrupts
> + */
> +static void mxs_auart_enable_ms(struct uart_port *port)
> +{
> +	struct mxs_auart_port *s = to_auart_port(port);
> +
> +	/*
> +	 * Interrupt should not be enabled twice
> +	 */
> +	if (s->ms_irq_enabled)
> +		return;
> +
> +	s->ms_irq_enabled = true;
> +
> +	if (s->gpio_irq[UART_GPIO_CTS] >= 0)
> +		enable_irq(s->gpio_irq[UART_GPIO_CTS]);
> +	/* TODO: enable AUART_INTR_CTSMIEN otherwise */
> +
> +	if (s->gpio_irq[UART_GPIO_DSR] >= 0)
> +		enable_irq(s->gpio_irq[UART_GPIO_DSR]);
> +
> +	if (s->gpio_irq[UART_GPIO_RI] >= 0)
> +		enable_irq(s->gpio_irq[UART_GPIO_RI]);
> +
> +	if (s->gpio_irq[UART_GPIO_DCD] >= 0)
> +		enable_irq(s->gpio_irq[UART_GPIO_DCD]);
> +}
> +
> +/*
> + * Disable modem status interrupts
> + */
> +static void mxs_auart_disable_ms(struct uart_port *port)
> +{
> +	struct mxs_auart_port *s = to_auart_port(port);
> +
> +	/*
> +	 * Interrupt should not be disabled twice
> +	 */
> +	if (!s->ms_irq_enabled)
> +		return;
> +
> +	s->ms_irq_enabled = false;
> +
> +	if (s->gpio_irq[UART_GPIO_CTS] >= 0)
> +		disable_irq(s->gpio_irq[UART_GPIO_CTS]);
> +	/* TODO: disable AUART_INTR_CTSMIEN otherwise */
> +
> +	if (s->gpio_irq[UART_GPIO_DSR] >= 0)
> +		disable_irq(s->gpio_irq[UART_GPIO_DSR]);
> +
> +	if (s->gpio_irq[UART_GPIO_RI] >= 0)
> +		disable_irq(s->gpio_irq[UART_GPIO_RI]);
> +
> +	if (s->gpio_irq[UART_GPIO_DCD] >= 0)
> +		disable_irq(s->gpio_irq[UART_GPIO_DCD]);
> +}
> +
>  static int mxs_auart_dma_prep_rx(struct mxs_auart_port *s);
>  static void dma_rx_callback(void *arg)
>  {
> @@ -692,6 +779,12 @@ static void mxs_auart_settermios(struct uart_port *u,
>  			dev_err(s->dev, "We can not start up the DMA.\n");
>  		}
>  	}
> +
> +	/* CTS flow-control and modem-status interrupts */
> +	if (UART_ENABLE_MS(u, termios->c_cflag))
> +		mxs_auart_enable_ms(u);
> +	else
> +		mxs_auart_disable_ms(u);
>  }
>  
>  static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
> @@ -709,9 +802,20 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
>  		| AUART_INTR_CTSMIS),
>  			s->port.membase + AUART_INTR_CLR);
>  
> +	/*
> +	 * Dealing with GPIO interrupt
> +	 */
> +	if (irq == s->gpio_irq[UART_GPIO_CTS] ||
> +	    irq == s->gpio_irq[UART_GPIO_DCD] ||
> +	    irq == s->gpio_irq[UART_GPIO_DSR] ||
> +	    irq == s->gpio_irq[UART_GPIO_RI])
> +		mxs_auart_modem_status(s,
> +				mctrl_gpio_get(s->gpios, &s->mctrl_prev));
> +
>  	if (istat & AUART_INTR_CTSMIS) {
>  		if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(s->gpios,
> -						UART_GPIO_CTS)))
> +							UART_GPIO_CTS))
> +						&& s->ms_irq_enabled)
>  			uart_handle_cts_change(&s->port,
>  					stat & AUART_STAT_CTS);
>  		writel(AUART_INTR_CTSMIS,
> @@ -774,6 +878,10 @@ 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->mctrl_prev);
> +
> +	s->ms_irq_enabled = false;
>  	return 0;
>  }
>  
> @@ -781,6 +889,8 @@ static void mxs_auart_shutdown(struct uart_port *u)
>  {
>  	struct mxs_auart_port *s = to_auart_port(u);
>  
> +	mxs_auart_disable_ms(u);
> +
>  	if (auart_dma_enabled(s))
>  		mxs_auart_dma_exit(s);
>  
> @@ -837,6 +947,7 @@ static struct uart_ops mxs_auart_ops = {
>  	.start_tx       = mxs_auart_start_tx,
>  	.stop_tx	= mxs_auart_stop_tx,
>  	.stop_rx	= mxs_auart_stop_rx,
> +	.enable_ms      = mxs_auart_enable_ms,
>  	.break_ctl      = mxs_auart_break_ctl,
>  	.set_mctrl	= mxs_auart_set_mctrl,
>  	.get_mctrl      = mxs_auart_get_mctrl,
> @@ -1039,12 +1150,61 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
>  
>  static int mxs_auart_init_gpios(struct mxs_auart_port *s, struct device *dev)
>  {
> +	enum mctrl_gpio_idx i;
> +	struct gpio_desc *gpiod;
> +
>  	s->gpios = mctrl_gpio_init(dev, 0);
>  	if (IS_ERR_OR_NULL(s->gpios))
>  		return -1;
> +
> +	for (i = 0; i < UART_GPIO_MAX; i++) {
> +		gpiod = mctrl_gpio_to_gpiod(s->gpios, i);
> +		if (gpiod && (gpiod_get_direction(gpiod) == GPIOF_DIR_IN))
> +			s->gpio_irq[i] = gpiod_to_irq(gpiod);
> +		else
> +			s->gpio_irq[i] = -EINVAL;
> +	}
> +
>  	return 0;
>  }
>  
> +static void mxs_auart_free_gpio_irq(struct mxs_auart_port *s)
> +{
> +	enum mctrl_gpio_idx i;
> +
> +	for (i = 0; i < UART_GPIO_MAX; i++)
> +		if (s->gpio_irq[i] >= 0)
> +			free_irq(s->gpio_irq[i], s);
> +}
> +
> +static int mxs_auart_request_gpio_irq(struct mxs_auart_port *s)
> +{
> +	int *irq = s->gpio_irq;
> +	enum mctrl_gpio_idx i;
> +	int err = 0;
> +
> +	for (i = 0; (i < UART_GPIO_MAX) && !err; i++) {
> +		if (irq[i] < 0)
> +			continue;
> +
> +		irq_set_status_flags(irq[i], IRQ_NOAUTOEN);
> +		err = request_irq(irq[i], mxs_auart_irq_handle,
> +				IRQ_TYPE_EDGE_BOTH, dev_name(s->dev), s);
> +		if (err)
> +			dev_err(s->dev, "%s - Can't get %d irq\n",
> +				__func__, irq[i]);
> +	}
> +
> +	/*
> +	 * If something went wrong, rollback.
> +	 */
> +	while (err && (--i >= 0))
> +		if (irq[i] >= 0)
> +			free_irq(irq[i], s);
> +
> +	return err;
> +}
> +
>  static int mxs_auart_probe(struct platform_device *pdev)
>  {
>  	const struct of_device_id *of_id =
> @@ -1092,6 +1252,8 @@ static int mxs_auart_probe(struct platform_device *pdev)
>  	s->port.type = PORT_IMX;
>  	s->port.dev = s->dev = &pdev->dev;
>  
> +	s->mctrl_prev = 0;
> +
>  	s->irq = platform_get_irq(pdev, 0);
>  	s->port.irq = s->irq;
>  	ret = request_irq(s->irq, mxs_auart_irq_handle, 0, dev_name(&pdev->dev), s);
> @@ -1105,13 +1267,20 @@ static int mxs_auart_probe(struct platform_device *pdev)
>  		dev_err(&pdev->dev, "%s",
>  			"Failed to initialize GPIOs. The serial port may not work as expected");
>  
> +	/*
> +	 * Get the GPIO lines IRQ
> +	 */
> +	ret = mxs_auart_request_gpio_irq(s);
> +	if (ret)
> +		goto out_free_irq;
> +
>  	auart_port[s->port.line] = s;
>  
>  	mxs_auart_reset(&s->port);
>  
>  	ret = uart_add_one_port(&auart_driver, &s->port);
>  	if (ret)
> -		goto out_free_irq;
> +		goto out_free_gpio_irq;
>  
>  	version = readl(s->port.membase + AUART_VERSION);
>  	dev_info(&pdev->dev, "Found APPUART %d.%d.%d\n",
> @@ -1120,6 +1289,8 @@ static int mxs_auart_probe(struct platform_device *pdev)
>  
>  	return 0;
>  
> +out_free_gpio_irq:
> +	mxs_auart_free_gpio_irq(s);
>  out_free_irq:
>  	auart_port[pdev->id] = NULL;
>  	free_irq(s->irq, s);
> @@ -1139,6 +1310,7 @@ static int mxs_auart_remove(struct platform_device *pdev)
>  
>  	auart_port[pdev->id] = NULL;
>  
> +	mxs_auart_free_gpio_irq(s);
>  	clk_put(s->clk);
>  	free_irq(s->irq, s);
>  	kfree(s);
> 
Seems also ok.
Janusz, will you provide a patch to complete {en,dis}able_ms functions
for non-gpio ?

Reviewed-by: Richard Genoud <[email-masked]>