tty/serial: at91: use mctrl_gpio helpers

On sam9x5, dedicated CTS (and RTS) pins are unusable together with the
LCDC, the EMAC, or the MMC because they share the same line.

Moreover, the USART 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: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 71 insertions, 35 deletions

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 4bf6d220357b..fb57159bad3a 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -117,6 +117,7 @@ config SERIAL_ATMEL
         bool "AT91 / AT32 on-chip serial port support"
         depends on ARCH_AT91 || AVR32
         select SERIAL_CORE
+        select SERIAL_MCTRL_GPIO
         help
           This enables the driver for the on-chip UARTs of the Atmel
           AT91 and AT32 processors.
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 53eeea13ff16..43ca659c1d4b 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -43,6 +43,8 @@
 #include <linux/platform_data/atmel.h>
 #include <linux/timer.h>
 #include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/err.h>
 
 #include <asm/io.h>
 #include <asm/ioctls.h>
@@ -57,6 +59,8 @@
 
 #include <linux/serial_core.h>
 
+#include "serial_mctrl_gpio.h"
+
 static void atmel_start_rx(struct uart_port *port);
 static void atmel_stop_rx(struct uart_port *port);
 
@@ -162,7 +166,7 @@ struct atmel_uart_port {
         struct circ_buf         rx_ring;
 
         struct serial_rs485     rs485;          /* rs485 settings */
-        int                     rts_gpio;       /* optional RTS GPIO */
+        struct mctrl_gpios      *gpios;
         unsigned int            tx_done_mask;
         bool                    is_usart;       /* usart or uart */
         struct timer_list       uart_timer;     /* uart timer */
@@ -237,6 +241,50 @@ static bool atmel_use_dma_rx(struct uart_port *port)
         return atmel_port->use_dma_rx;
 }
 
+static unsigned int atmel_get_lines_status(struct uart_port *port)
+{
+        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+        unsigned int status, ret = 0;
+
+        status = UART_GET_CSR(port);
+
+        mctrl_gpio_get(atmel_port->gpios, &ret);
+
+        if (!IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(atmel_port->gpios,
+                                                UART_GPIO_CTS))) {
+                if (ret & TIOCM_CTS)
+                        status &= ~ATMEL_US_CTS;
+                else
+                        status |= ATMEL_US_CTS;
+        }
+
+        if (!IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(atmel_port->gpios,
+                                                UART_GPIO_DSR))) {
+                if (ret & TIOCM_DSR)
+                        status &= ~ATMEL_US_DSR;
+                else
+                        status |= ATMEL_US_DSR;
+        }
+
+        if (!IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(atmel_port->gpios,
+                                                UART_GPIO_RI))) {
+                if (ret & TIOCM_RI)
+                        status &= ~ATMEL_US_RI;
+                else
+                        status |= ATMEL_US_RI;
+        }
+
+        if (!IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(atmel_port->gpios,
+                                                UART_GPIO_DCD))) {
+                if (ret & TIOCM_CD)
+                        status &= ~ATMEL_US_DCD;
+                else
+                        status |= ATMEL_US_DCD;
+        }
+
+        return status;
+}
+
 /* Enable or disable the rs485 support */
 void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
 {
@@ -296,17 +344,6 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
         unsigned int mode;
         struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-        /*
-         * AT91RM9200 Errata #39: RTS0 is not internally connected
-         * to PA21. We need to drive the pin as a GPIO.
-         */
-        if (gpio_is_valid(atmel_port->rts_gpio)) {
-                if (mctrl & TIOCM_RTS)
-                        gpio_set_value(atmel_port->rts_gpio, 0);
-                else
-                        gpio_set_value(atmel_port->rts_gpio, 1);
-        }
-
         if (mctrl & TIOCM_RTS)
                 control |= ATMEL_US_RTSEN;
         else
@@ -319,6 +356,8 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 
         UART_PUT_CR(port, control);
 
+        mctrl_gpio_set(atmel_port->gpios, mctrl);
+
         /* Local loopback mode? */
         mode = UART_GET_MR(port) & ~ATMEL_US_CHMODE;
         if (mctrl & TIOCM_LOOP)
@@ -346,7 +385,8 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
  */
 static u_int atmel_get_mctrl(struct uart_port *port)
 {
-        unsigned int status, ret = 0;
+        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+        unsigned int ret = 0, status;
 
         status = UART_GET_CSR(port);
 
@@ -362,7 +402,7 @@ static u_int atmel_get_mctrl(struct uart_port *port)
         if (!(status & ATMEL_US_RI))
                 ret |= TIOCM_RI;
 
-        return ret;
+        return mctrl_gpio_get(atmel_port->gpios, &ret);
 }
 
 /*
@@ -1042,7 +1082,7 @@ static irqreturn_t atmel_interrupt(int irq, void *dev_id)
         unsigned int status, pending, pass_counter = 0;
 
         do {
-                status = UART_GET_CSR(port);
+                status = atmel_get_lines_status(port);
                 pending = status & UART_GET_IMR(port);
                 if (!pending)
                         break;
@@ -1568,7 +1608,7 @@ static int atmel_startup(struct uart_port *port)
         }
 
         /* Save current CSR for comparison in atmel_tasklet_func() */
-        atmel_port->irq_status_prev = UART_GET_CSR(port);
+        atmel_port->irq_status_prev = atmel_get_lines_status(port);
         atmel_port->irq_status = atmel_port->irq_status_prev;
 
         /*
@@ -2324,6 +2364,15 @@ static int atmel_serial_resume(struct platform_device *pdev)
 #define atmel_serial_resume NULL
 #endif
 
+static int atmel_init_gpios(struct atmel_uart_port *p, struct device *dev)
+{
+        p->gpios = mctrl_gpio_init(dev, 0);
+        if (IS_ERR_OR_NULL(p->gpios))
+                return -1;
+
+        return 0;
+}
+
 static int atmel_serial_probe(struct platform_device *pdev)
 {
         struct atmel_uart_port *port;
@@ -2359,25 +2408,11 @@ static int atmel_serial_probe(struct platform_device *pdev)
         port = &atmel_ports[ret];
         port->backup_imr = 0;
         port->uart.line = ret;
-        port->rts_gpio = -EINVAL; /* Invalid, zero could be valid */
-        if (pdata)
-                port->rts_gpio = pdata->rts_gpio;
-        else if (np)
-                port->rts_gpio = of_get_named_gpio(np, "rts-gpios", 0);
-
-        if (gpio_is_valid(port->rts_gpio)) {
-                ret = devm_gpio_request(&pdev->dev, port->rts_gpio, "RTS");
-                if (ret) {
-                        dev_err(&pdev->dev, "error requesting RTS GPIO\n");
-                        goto err;
-                }
-                /* Default to 1 as RTS is active low */
-                ret = gpio_direction_output(port->rts_gpio, 1);
-                if (ret) {
-                        dev_err(&pdev->dev, "error setting up RTS GPIO\n");
-                        goto err;
-                }
-        }
+
+        ret = atmel_init_gpios(port, &pdev->dev);
+        if (ret < 0)
+                dev_err(&pdev->dev, "%s",
+                        "Failed to initialize GPIOs. The serial port may not work as expected");
 
         ret = atmel_init_port(port, pdev);
         if (ret)