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: Eric Miao <eric.miao@marvell.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arm/mach-pxa/include/mach/pxa2xx_spi.h b/arch/arm/mach-pxa/include/mach/pxa2xx_spi.h
index 2206cb6..b87cecd 100644 (file)
--- a/arch/arm/mach-pxa/include/mach/pxa2xx_spi.h
+++ b/arch/arm/mach-pxa/include/mach/pxa2xx_spi.h
@@ -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);
 };
 

diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
index 33fcef3..70ff007 100644 (file)
--- a/drivers/spi/pxa2xx_spi.c
+++ b/drivers/spi/pxa2xx_spi.c
@@ -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);
 }