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>

Documentation/devicetree/bindings/serial/atmel-usart.txt

@@ -10,6 +10,8 @@ Required properties:
 Optional properties:
 - atmel,use-dma-rx: use of PDC or DMA for receiving data
 - atmel,use-dma-tx: use of PDC or DMA for transmitting data
+- rts-gpios: specify a GPIO for RTS line. It will use specified PIO instead of the peripheral
+  function pin for the USART RTS feature. If unsure, don't specify this property.
 - add dma bindings for dma transfer:
 	- dmas: DMA specifier, consisting of a phandle to DMA controller node,
 		memory peripheral interface and USART DMA channel ID, FIFO configuration.
@@ -28,6 +30,7 @@ Example:
 		interrupts = <7>;
 		atmel,use-dma-rx;
 		atmel,use-dma-tx;
+		rts-gpios = <&pioD 15 0>;
 	};
 
 - use DMA:

arch/arm/mach-at91/at91rm9200_devices.c

@@ -922,6 +922,7 @@ static struct resource dbgu_resources[] = {
 static struct atmel_uart_data dbgu_data = {
 	.use_dma_tx	= 0,
 	.use_dma_rx	= 0,		/* DBGU not capable of receive DMA */
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 dbgu_dmamask = DMA_BIT_MASK(32);
@@ -960,6 +961,7 @@ static struct resource uart0_resources[] = {
 static struct atmel_uart_data uart0_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart0_dmamask = DMA_BIT_MASK(32);
@@ -987,9 +989,10 @@ static inline void configure_usart0_pins(unsigned pins)
 	if (pins & ATMEL_UART_RTS) {
 		/*
 		 * AT91RM9200 Errata #39 - RTS0 is not internally connected to PA21.
-		 *  We need to drive the pin manually.  Default is off (RTS is active low).
+		 * We need to drive the pin manually. The serial driver will driver
+		 * this to high when initializing.
 		 */
-		at91_set_gpio_output(AT91_PIN_PA21, 1);
+		uart0_data.rts_gpio = AT91_PIN_PA21;
 	}
 }
 
@@ -1009,6 +1012,7 @@ static struct resource uart1_resources[] = {
 static struct atmel_uart_data uart1_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart1_dmamask = DMA_BIT_MASK(32);
@@ -1060,6 +1064,7 @@ static struct resource uart2_resources[] = {
 static struct atmel_uart_data uart2_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart2_dmamask = DMA_BIT_MASK(32);
@@ -1103,6 +1108,7 @@ static struct resource uart3_resources[] = {
 static struct atmel_uart_data uart3_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart3_dmamask = DMA_BIT_MASK(32);

arch/arm/mach-at91/at91sam9260_devices.c

@@ -819,6 +819,7 @@ static struct resource dbgu_resources[] = {
 static struct atmel_uart_data dbgu_data = {
 	.use_dma_tx	= 0,
 	.use_dma_rx	= 0,		/* DBGU not capable of receive DMA */
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 dbgu_dmamask = DMA_BIT_MASK(32);
@@ -857,6 +858,7 @@ static struct resource uart0_resources[] = {
 static struct atmel_uart_data uart0_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart0_dmamask = DMA_BIT_MASK(32);
@@ -908,6 +910,7 @@ static struct resource uart1_resources[] = {
 static struct atmel_uart_data uart1_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart1_dmamask = DMA_BIT_MASK(32);
@@ -951,6 +954,7 @@ static struct resource uart2_resources[] = {
 static struct atmel_uart_data uart2_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart2_dmamask = DMA_BIT_MASK(32);
@@ -994,6 +998,7 @@ static struct resource uart3_resources[] = {
 static struct atmel_uart_data uart3_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart3_dmamask = DMA_BIT_MASK(32);
@@ -1037,6 +1042,7 @@ static struct resource uart4_resources[] = {
 static struct atmel_uart_data uart4_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart4_dmamask = DMA_BIT_MASK(32);
@@ -1075,6 +1081,7 @@ static struct resource uart5_resources[] = {
 static struct atmel_uart_data uart5_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart5_dmamask = DMA_BIT_MASK(32);

arch/arm/mach-at91/at91sam9261_devices.c

@@ -880,6 +880,7 @@ static struct resource dbgu_resources[] = {
 static struct atmel_uart_data dbgu_data = {
 	.use_dma_tx	= 0,
 	.use_dma_rx	= 0,		/* DBGU not capable of receive DMA */
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 dbgu_dmamask = DMA_BIT_MASK(32);
@@ -918,6 +919,7 @@ static struct resource uart0_resources[] = {
 static struct atmel_uart_data uart0_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart0_dmamask = DMA_BIT_MASK(32);
@@ -961,6 +963,7 @@ static struct resource uart1_resources[] = {
 static struct atmel_uart_data uart1_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart1_dmamask = DMA_BIT_MASK(32);
@@ -1004,6 +1007,7 @@ static struct resource uart2_resources[] = {
 static struct atmel_uart_data uart2_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart2_dmamask = DMA_BIT_MASK(32);

arch/arm/mach-at91/at91sam9263_devices.c

@@ -1324,6 +1324,7 @@ static struct resource dbgu_resources[] = {
 static struct atmel_uart_data dbgu_data = {
 	.use_dma_tx	= 0,
 	.use_dma_rx	= 0,		/* DBGU not capable of receive DMA */
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 dbgu_dmamask = DMA_BIT_MASK(32);
@@ -1362,6 +1363,7 @@ static struct resource uart0_resources[] = {
 static struct atmel_uart_data uart0_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart0_dmamask = DMA_BIT_MASK(32);
@@ -1405,6 +1407,7 @@ static struct resource uart1_resources[] = {
 static struct atmel_uart_data uart1_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart1_dmamask = DMA_BIT_MASK(32);
@@ -1448,6 +1451,7 @@ static struct resource uart2_resources[] = {
 static struct atmel_uart_data uart2_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart2_dmamask = DMA_BIT_MASK(32);

arch/arm/mach-at91/at91sam9g45_devices.c

@@ -1587,6 +1587,7 @@ static struct resource dbgu_resources[] = {
 static struct atmel_uart_data dbgu_data = {
 	.use_dma_tx	= 0,
 	.use_dma_rx	= 0,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 dbgu_dmamask = DMA_BIT_MASK(32);
@@ -1625,6 +1626,7 @@ static struct resource uart0_resources[] = {
 static struct atmel_uart_data uart0_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart0_dmamask = DMA_BIT_MASK(32);
@@ -1668,6 +1670,7 @@ static struct resource uart1_resources[] = {
 static struct atmel_uart_data uart1_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart1_dmamask = DMA_BIT_MASK(32);
@@ -1711,6 +1714,7 @@ static struct resource uart2_resources[] = {
 static struct atmel_uart_data uart2_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart2_dmamask = DMA_BIT_MASK(32);
@@ -1754,6 +1758,7 @@ static struct resource uart3_resources[] = {
 static struct atmel_uart_data uart3_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart3_dmamask = DMA_BIT_MASK(32);

arch/arm/mach-at91/at91sam9rl_devices.c

@@ -956,6 +956,7 @@ static struct resource dbgu_resources[] = {
 static struct atmel_uart_data dbgu_data = {
 	.use_dma_tx	= 0,
 	.use_dma_rx	= 0,		/* DBGU not capable of receive DMA */
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 dbgu_dmamask = DMA_BIT_MASK(32);
@@ -994,6 +995,7 @@ static struct resource uart0_resources[] = {
 static struct atmel_uart_data uart0_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart0_dmamask = DMA_BIT_MASK(32);
@@ -1045,6 +1047,7 @@ static struct resource uart1_resources[] = {
 static struct atmel_uart_data uart1_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart1_dmamask = DMA_BIT_MASK(32);
@@ -1088,6 +1091,7 @@ static struct resource uart2_resources[] = {
 static struct atmel_uart_data uart2_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart2_dmamask = DMA_BIT_MASK(32);
@@ -1131,6 +1135,7 @@ static struct resource uart3_resources[] = {
 static struct atmel_uart_data uart3_data = {
 	.use_dma_tx	= 1,
 	.use_dma_rx	= 1,
+	.rts_gpio	= -EINVAL,
 };
 
 static u64 uart3_dmamask = DMA_BIT_MASK(32);

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)

include/linux/platform_data/atmel.h

@@ -84,6 +84,7 @@ struct atmel_uart_data {
 	short			use_dma_rx;	/* use receive DMA? */
 	void __iomem		*regs;		/* virt. base address, if any */
 	struct serial_rs485	rs485;		/* rs485 settings */
+	int			rts_gpio;	/* optional RTS GPIO */
 };
 
  /* Touchscreen Controller */