ARM/serial: at91: switch atmel serial to use gpiolib

This passes the errata fix using a GPIO to control the RTS pin
on one of the AT91 chips to use gpiolib instead of the
AT91-specific interfaces. Also remove the reliance on
compile-time #defines and the cpu_* check and rely on the
platform passing down the proper GPIO pin through platform
data.

This is a prerequisite for getting rid of the local GPIO
implementation in the AT91 platform and move toward
multiplatform.

The patch also adds device tree support for getting the
RTS GPIO pin from the device tree on DT boot paths.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

1 files changed, 31 insertions, 18 deletions

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index c7d99af46a96..40d6c9b0d98b 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -35,21 +35,18 @@
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_gpio.h>
 #include <linux/dma-mapping.h>
 #include <linux/atmel_pdc.h>
 #include <linux/atmel_serial.h>
 #include <linux/uaccess.h>
 #include <linux/platform_data/atmel.h>
 #include <linux/timer.h>
+#include <linux/gpio.h>
 
 #include <asm/io.h>
 #include <asm/ioctls.h>
 
-#ifdef CONFIG_ARM
-#include <mach/cpu.h>
-#include <asm/gpio.h>
-#endif
-
 #define PDC_BUFFER_SIZE         512
 /* Revisit: We should calculate this based on the actual port settings */
 #define PDC_RX_TIMEOUT          (3 * 10)                /* 3 bytes */
@@ -168,6 +165,7 @@ struct atmel_uart_port {
         struct circ_buf         rx_ring;
 
         struct serial_rs485     rs485;          /* rs485 settings */
+        int                     rts_gpio;       /* optional RTS GPIO */
         unsigned int            tx_done_mask;
         bool                    is_usart;       /* usart or uart */
         struct timer_list       uart_timer;     /* uart timer */
@@ -301,20 +299,16 @@ 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);
 
-#ifdef CONFIG_ARCH_AT91RM9200
-        if (cpu_is_at91rm9200()) {
-                /*
-                 * AT91RM9200 Errata #39: RTS0 is not internally connected
-                 * to PA21. We need to drive the pin manually.
-                 */
-                if (port->mapbase == AT91RM9200_BASE_US0) {
-                        if (mctrl & TIOCM_RTS)
-                                at91_set_gpio_value(AT91_PIN_PA21, 0);
-                        else
-                                at91_set_gpio_value(AT91_PIN_PA21, 1);
-                }
+        /*
+         * 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);
         }
-#endif
 
         if (mctrl & TIOCM_RTS)
                 control |= ATMEL_US_RTSEN;
@@ -2379,6 +2373,25 @@ 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_port(port, pdev);
         if (ret)