The patch titled
spi: pxa2xx_spi: introduce chipselect GPIO to simplify the common cases
has been added to the -mm tree. Its filename is
spi-pxa2xx_spi-introduces-chipselect-gpio-to-simplify-the-common-cases.patch
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------------------------------------------------------
Subject: spi: pxa2xx_spi: introduce chipselect GPIO to simplify the common cases
From: Eric Miao <eric.miao@xxxxxxxxxxx>
Most SPI peripherals use GPIOs as their chip selects, introduce .gpio_cs
for this.
Signed-off-by: Eric Miao <eric.miao@xxxxxxxxxxx>
Cc: David Brownell <david-b@xxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/mach-pxa/include/mach/pxa2xx_spi.h | 1
drivers/spi/pxa2xx_spi.c | 96 ++++++++++++++----
2 files changed, 79 insertions(+), 18 deletions(-)
diff -puN arch/arm/mach-pxa/include/mach/pxa2xx_spi.h~spi-pxa2xx_spi-introduces-chipselect-gpio-to-simplify-the-common-cases arch/arm/mach-pxa/include/mach/pxa2xx_spi.h
--- a/arch/arm/mach-pxa/include/mach/pxa2xx_spi.h~spi-pxa2xx_spi-introduces-chipselect-gpio-to-simplify-the-common-cases
+++ a/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 -puN drivers/spi/pxa2xx_spi.c~spi-pxa2xx_spi-introduces-chipselect-gpio-to-simplify-the-common-cases drivers/spi/pxa2xx_spi.c
--- a/drivers/spi/pxa2xx_spi.c~spi-pxa2xx_spi-introduces-chipselect-gpio-to-simplify-the-common-cases
+++ a/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
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
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
* 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
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
/* 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
}
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
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 *s
/* 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);
}
_
Patches currently in -mm which might be from eric.miao@xxxxxxxxxxx are
linux-next.patch
spi-pxa2xx_spi-introduces-chipselect-gpio-to-simplify-the-common-cases.patch
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