Subject: [PATCH v4] ARM/serial: at91: switch atmel serial to use gpiolib

From: [email-masked] (Nicolas Ferre)
Date: Wed, 13 Nov 2013 17:28:55 +0100

On 07/11/2013 10:25, Linus Walleij :
> 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 <[email-masked]>
> Acked-by: Jean-Christophe PLAGNIOL-VILLARD <[email-masked]>
> Signed-off-by: Linus Walleij <[email-masked]>

Hi Greg,

You acknowledged a previous version of this patch which was taking a 
different approach with the subject:
"[PATCH 1/4] ARM/serial: at91: move machine quirk into machine"

In order to integrate the series build by Linus in our AT91/arm-soc 
flow, would you mind reviewing this v4 patch and eventually giving your 
blessing ;-)
If it is okay on your side, I'll integrate it in a pull-request to 
arm-soc for 3.14.

Thanks, bye,

> ---
> ChangeLog v3->v4:
> - Assign RTS pin setup at runtime for the applicable
>    platforms. Drive it to 1 rather than 0 by default as
>    RTS is active low. Thanks to Jean-Christophe for noticing
>    the fine details... sorry for the fuzz :-/
> ChangeLog v2->v3:
> - Instead of disallowing GPIO 0 to be used for the RTS
>    signal to allow null-initialized platform data to mean
>    "no RTS GPIO", be more generic and actually allow it,
>    and patch every instance of atmel_uart_data to set
>    .rts_gpio to -EINVAL except for the one case where we
>    actually use pin 21 for RTS over GPIO.
> ChangeLog v1->v2:
> - Skip check for UART base address from leftover hack,
>    if we have an RTS GPIO we just use it.
> - Set default error value on GPIO pin to -EINVAL
> - Fold in a device tree support patch from Nicolas Ferre
> ---
>   .../devicetree/bindings/serial/atmel-usart.txt     |  3 ++
>   arch/arm/mach-at91/at91rm9200_devices.c            | 10 ++++-
>   arch/arm/mach-at91/at91sam9260_devices.c           |  7 ++++
>   arch/arm/mach-at91/at91sam9261_devices.c           |  4 ++
>   arch/arm/mach-at91/at91sam9263_devices.c           |  4 ++
>   arch/arm/mach-at91/at91sam9g45_devices.c           |  5 +++
>   arch/arm/mach-at91/at91sam9rl_devices.c            |  5 +++
>   drivers/tty/serial/atmel_serial.c                  | 49 ++++++++++++++--------
>   include/linux/platform_data/atmel.h                |  1 +
>   9 files changed, 68 insertions(+), 20 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/serial/atmel-usart.txt b/Documentation/devicetree/bindings/serial/atmel-usart.txt
> index 2191dcb9f1da..3adc61c2e4ca 100644
> --- a/Documentation/devicetree/bindings/serial/atmel-usart.txt
> +++ b/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:
> diff --git a/arch/arm/mach-at91/at91rm9200_devices.c b/arch/arm/mach-at91/at91rm9200_devices.c
> index c721e9b08066..08ac5e2ff97d 100644
> --- a/arch/arm/mach-at91/at91rm9200_devices.c
> +++ b/arch/arm/mach-at91/at91rm9200_devices.c
> @@ -923,6 +923,7 @@ 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);
> @@ -961,6 +962,7 @@ 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);
> @@ -988,9 +990,10 @@ 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;
>   	}
>   }
>
> @@ -1010,6 +1013,7 @@ 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);
> @@ -1061,6 +1065,7 @@ 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);
> @@ -1104,6 +1109,7 @@ 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);
> diff --git a/arch/arm/mach-at91/at91sam9260_devices.c b/arch/arm/mach-at91/at91sam9260_devices.c
> index 428abfc14848..bcf4a161a3d8 100644
> --- a/arch/arm/mach-at91/at91sam9260_devices.c
> +++ b/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);
> diff --git a/arch/arm/mach-at91/at91sam9261_devices.c b/arch/arm/mach-at91/at91sam9261_devices.c
> index 4e02e9271ac9..d5b08ef9e848 100644
> --- a/arch/arm/mach-at91/at91sam9261_devices.c
> +++ b/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);
> diff --git a/arch/arm/mach-at91/at91sam9263_devices.c b/arch/arm/mach-at91/at91sam9263_devices.c
> index 3a384ef27cf6..22b13c6226cb 100644
> --- a/arch/arm/mach-at91/at91sam9263_devices.c
> +++ b/arch/arm/mach-at91/at91sam9263_devices.c
> @@ -1325,6 +1325,7 @@ 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);
> @@ -1363,6 +1364,7 @@ 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);
> @@ -1406,6 +1408,7 @@ 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);
> @@ -1449,6 +1452,7 @@ 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);
> diff --git a/arch/arm/mach-at91/at91sam9g45_devices.c b/arch/arm/mach-at91/at91sam9g45_devices.c
> index 6b8effbffc28..89f95ed711c6 100644
> --- a/arch/arm/mach-at91/at91sam9g45_devices.c
> +++ b/arch/arm/mach-at91/at91sam9g45_devices.c
> @@ -1588,6 +1588,7 @@ 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);
> @@ -1626,6 +1627,7 @@ 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);
> @@ -1669,6 +1671,7 @@ 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);
> @@ -1712,6 +1715,7 @@ 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);
> @@ -1755,6 +1759,7 @@ 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);
> diff --git a/arch/arm/mach-at91/at91sam9rl_devices.c b/arch/arm/mach-at91/at91sam9rl_devices.c
> index 6cf441cadf94..3c2462b15b8b 100644
> --- a/arch/arm/mach-at91/at91sam9rl_devices.c
> +++ b/arch/arm/mach-at91/at91sam9rl_devices.c
> @@ -957,6 +957,7 @@ 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);
> @@ -995,6 +996,7 @@ 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);
> @@ -1046,6 +1048,7 @@ 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);
> @@ -1089,6 +1092,7 @@ 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);
> @@ -1132,6 +1136,7 @@ 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);
> diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
> index d067285a2d20..af6765d3aedb 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 */
> @@ -167,6 +164,7 @@ 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 */
> @@ -300,20 +298,16 @@ 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;
> @@ -2365,6 +2359,25 @@ 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)
> diff --git a/include/linux/platform_data/atmel.h b/include/linux/platform_data/atmel.h
> index cea9f70133c5..e26b0c14edea 100644
> --- a/include/linux/platform_data/atmel.h
> +++ b/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 */
>

-- 
Nicolas Ferre