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Commit a7bb3909 authored by Eric Miao's avatar Eric Miao Committed by Linus Torvalds
Browse files

spi: pxa2xx_spi: introduce chipselect GPIO to simplify the common cases 



Most SPI peripherals use GPIOs as their chip selects, introduce .gpio_cs
for this.

Signed-off-by: default avatarEric Miao <eric.miao@marvell.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8fc657e

arch/arm/mach-pxa/include/mach/pxa2xx_spi.h

+1 −0
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ struct pxa2xx_spi_chip { 
	u8 dma_burst_size;

	u32 timeout;

	u8 enable_loopback;

	int gpio_cs;

	void (*cs_control)(u32 command);

};

drivers/spi/pxa2xx_spi.c

+78 −18
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/workqueue.h>

#include <linux/delay.h>

#include <linux/clk.h>

#include <linux/gpio.h>



#include <asm/io.h>

#include <asm/irq.h>
@@ -166,6 +167,8 @@ struct chip_data { 
	u8 enable_dma;

	u8 bits_per_word;

	u32 speed_hz;

	int gpio_cs;

	int gpio_cs_inverted;

	int (*write)(struct driver_data *drv_data);

	int (*read)(struct driver_data *drv_data);

	void (*cs_control)(u32 command);
@@ -173,6 +176,32 @@ struct chip_data { 


static void pump_messages(struct work_struct *work);



static void cs_assert(struct driver_data *drv_data)

{

	struct chip_data *chip = drv_data->cur_chip;



	if (chip->cs_control) {

		chip->cs_control(PXA2XX_CS_ASSERT);

		return;

	}



	if (gpio_is_valid(chip->gpio_cs))

		gpio_set_value(chip->gpio_cs, chip->gpio_cs_inverted);

}



static void cs_deassert(struct driver_data *drv_data)

{

	struct chip_data *chip = drv_data->cur_chip;



	if (chip->cs_control) {

		chip->cs_control(PXA2XX_CS_ASSERT);

		return;

	}



	if (gpio_is_valid(chip->gpio_cs))

		gpio_set_value(chip->gpio_cs, !chip->gpio_cs_inverted);

}



static int flush(struct driver_data *drv_data)

{

	unsigned long limit = loops_per_jiffy << 1;
@@ -189,10 +218,6 @@ static int flush(struct driver_data *drv_data) 
	return limit;

}



static void null_cs_control(u32 command)

{

}



static int null_writer(struct driver_data *drv_data)

{

	void __iomem *reg = drv_data->ioaddr;
@@ -400,7 +425,6 @@ static void giveback(struct driver_data *drv_data) 
	msg = drv_data->cur_msg;

	drv_data->cur_msg = NULL;

	drv_data->cur_transfer = NULL;

	drv_data->cur_chip = NULL;

	queue_work(drv_data->workqueue, &drv_data->pump_messages);

	spin_unlock_irqrestore(&drv_data->lock, flags);
@@ -416,7 +440,7 @@ static void giveback(struct driver_data *drv_data) 
	 * a message with an error, or next message is for another chip

	 */

	if (!last_transfer->cs_change)

		drv_data->cs_control(PXA2XX_CS_DEASSERT);

		cs_deassert(drv_data);

	else {

		struct spi_message *next_msg;
@@ -445,12 +469,14 @@ static void giveback(struct driver_data *drv_data) 
		if (next_msg && next_msg->spi != msg->spi)

			next_msg = NULL;

		if (!next_msg || msg->state == ERROR_STATE)

			drv_data->cs_control(PXA2XX_CS_DEASSERT);

			cs_deassert(drv_data);

	}



	msg->state = NULL;

	if (msg->complete)

		msg->complete(msg->context);



	drv_data->cur_chip = NULL;

}



static int wait_ssp_rx_stall(void const __iomem *ioaddr)
@@ -887,7 +913,7 @@ static void pump_transfers(unsigned long data) 


		/* Drop chip select only if cs_change is requested */

		if (previous->cs_change)

			drv_data->cs_control(PXA2XX_CS_DEASSERT);

			cs_deassert(drv_data);

	}



	/* Check for transfers that need multiple DMA segments */
@@ -922,7 +948,6 @@ static void pump_transfers(unsigned long data) 
	}

	drv_data->n_bytes = chip->n_bytes;

	drv_data->dma_width = chip->dma_width;

	drv_data->cs_control = chip->cs_control;

	drv_data->tx = (void *)transfer->tx_buf;

	drv_data->tx_end = drv_data->tx + transfer->len;

	drv_data->rx = transfer->rx_buf;
@@ -1084,11 +1109,7 @@ static void pump_transfers(unsigned long data) 
			write_SSTO(chip->timeout, reg);

	}



	/* FIXME, need to handle cs polarity,

	 * this driver uses struct pxa2xx_spi_chip.cs_control to

	 * specify a CS handling function, and it ignores most

	 * struct spi_device.mode[s], including SPI_CS_HIGH */

	drv_data->cs_control(PXA2XX_CS_ASSERT);

	cs_assert(drv_data);



	/* after chip select, release the data by enabling service

	 * requests and interrupts, without changing any mode bits */
@@ -1166,6 +1187,44 @@ static int transfer(struct spi_device *spi, struct spi_message *msg) 
/* the spi->mode bits understood by this driver: */

#define MODEBITS (SPI_CPOL | SPI_CPHA)



static int setup_cs(struct spi_device *spi, struct chip_data *chip,

		    struct pxa2xx_spi_chip *chip_info)

{

	int err = 0;



	if (chip == NULL || chip_info == NULL)

		return 0;



	/* NOTE: setup() can be called multiple times, possibly with

	 * different chip_info, release previously requested GPIO

	 */

	if (gpio_is_valid(chip->gpio_cs))

		gpio_free(chip->gpio_cs);



	/* If (*cs_control) is provided, ignore GPIO chip select */

	if (chip_info->cs_control) {

		chip->cs_control = chip_info->cs_control;

		return 0;

	}



	if (gpio_is_valid(chip_info->gpio_cs)) {

		err = gpio_request(chip_info->gpio_cs, "SPI_CS");

		if (err) {

			dev_err(&spi->dev, "failed to request chip select "

					"GPIO%d\n", chip_info->gpio_cs);

			return err;

		}



		chip->gpio_cs = chip_info->gpio_cs;

		chip->gpio_cs_inverted = spi->mode & SPI_CS_HIGH;



		err = gpio_direction_output(chip->gpio_cs,

					!chip->gpio_cs_inverted);

	}



	return err;

}



static int setup(struct spi_device *spi)

{

	struct pxa2xx_spi_chip *chip_info = NULL;
@@ -1211,7 +1270,7 @@ static int setup(struct spi_device *spi) 
			return -ENOMEM;

		}



		chip->cs_control = null_cs_control;

		chip->gpio_cs = -1;

		chip->enable_dma = 0;

		chip->timeout = TIMOUT_DFLT;

		chip->dma_burst_size = drv_data->master_info->enable_dma ?
@@ -1225,8 +1284,6 @@ static int setup(struct spi_device *spi) 
	/* chip_info isn't always needed */

	chip->cr1 = 0;

	if (chip_info) {

		if (chip_info->cs_control)

			chip->cs_control = chip_info->cs_control;

		if (chip_info->timeout)

			chip->timeout = chip_info->timeout;

		if (chip_info->tx_threshold)
@@ -1308,13 +1365,16 @@ static int setup(struct spi_device *spi) 


	spi_set_ctldata(spi, chip);



	return 0;

	return setup_cs(spi, chip, chip_info);

}



static void cleanup(struct spi_device *spi)

{

	struct chip_data *chip = spi_get_ctldata(spi);



	if (gpio_is_valid(chip->gpio_cs))

		gpio_free(chip->gpio_cs);



	kfree(chip);

}