The existing driver supports gpio based /cs signal.
For controller's that have one device per controller,
the slave device's /cs signal might be internally controlled
by the chip select bit of slave select register. They are not
externally asserted/deasserted using gpio pin.
This patch adds support for controllers with dedicated /cs pin.
if "cs-gpio" property doesnt exist in a spi dts node, the controller
would treat the /cs pin as dedicated.
Signed-off-by: Girish K S <ks.g...@samsung.com>
---
changes in v2:
added provision to use either gpio/dedicated pins as chip
select
drivers/spi/spi-s3c64xx.c | 27 +++++++++++++++++++--------
include/linux/platform_data/spi-s3c64xx.h | 3 +++
2 files changed, 22 insertions(+), 8 deletions(-)
diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index a8fe876..15b7ee9 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -416,14 +416,16 @@ static inline void enable_cs(struct
s3c64xx_spi_driver_data *sdd,
if (sdd->tgl_spi != spi) { /* if last mssg on diff device */
/* Deselect the last toggled device */
cs = sdd->tgl_spi->controller_data;
- gpio_set_value(cs->line,
- spi->mode & SPI_CS_HIGH ? 0 : 1);
+ if (cs->cs_gpio)
+ gpio_set_value(cs->line,
+ spi->mode & SPI_CS_HIGH ? 0 : 1);
}
sdd->tgl_spi = NULL;
}
cs = spi->controller_data;
- gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 1 : 0);
+ if (cs->cs_gpio)
+ gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 1 : 0);
/* Start the signals */
writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
@@ -552,7 +554,8 @@ static inline void disable_cs(struct
s3c64xx_spi_driver_data *sdd,
if (sdd->tgl_spi == spi)
sdd->tgl_spi = NULL;
- gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 0 : 1);
+ if (cs->cs_gpio)
+ gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 0 : 1);
/* Quiese the signals */
writel(S3C64XX_SPI_SLAVE_SIG_INACT,
@@ -891,7 +894,12 @@ static struct s3c64xx_spi_csinfo
*s3c64xx_get_slave_ctrldata(
return ERR_PTR(-ENOMEM);
}
- cs->line = of_get_named_gpio(data_np, "cs-gpio", 0);
+ if (of_find_property(data_np, "cs-gpio", NULL)) {
+ /* The CS line is asserted/deasserted by the gpio pin */
+ cs->cs_gpio = true;
+ cs->line = of_get_named_gpio(data_np, "cs-gpio", 0);
+ }
+
if (!gpio_is_valid(cs->line)) {
dev_err(&spi->dev, "chip select gpio is not specified or
invalid\n");
kfree(cs);
@@ -931,7 +939,8 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
return -ENODEV;
}
- if (!spi_get_ctldata(spi)) {
+ /* Request gpio only if cs line is asserted by gpio pins */
+ if (cs->cs_gpio) {
err = gpio_request_one(cs->line, GPIOF_OUT_INIT_HIGH,
dev_name(&spi->dev));
if (err) {
@@ -940,9 +949,11 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
cs->line, err);
goto err_gpio_req;
}
- spi_set_ctldata(spi, cs);
}
+ if (!spi_get_ctldata(spi))
+ spi_set_ctldata(spi, cs);
+
sci = sdd->cntrlr_info;
spin_lock_irqsave(&sdd->lock, flags);
@@ -1030,7 +1041,7 @@ static void s3c64xx_spi_cleanup(struct spi_device *spi)
{
struct s3c64xx_spi_csinfo *cs = spi_get_ctldata(spi);
- if (cs) {
+ if (cs && cs->cs_gpio) {
gpio_free(cs->line);
if (spi->dev.of_node)
kfree(cs);
diff --git a/include/linux/platform_data/spi-s3c64xx.h
b/include/linux/platform_data/spi-s3c64xx.h
index ceba18d..0343d8d 100644
--- a/include/linux/platform_data/spi-s3c64xx.h
+++ b/include/linux/platform_data/spi-s3c64xx.h
@@ -17,6 +17,8 @@ struct platform_device;
* struct s3c64xx_spi_csinfo - ChipSelect description
* @fb_delay: Slave specific feedback delay.
* Refer to FB_CLK_SEL register definition in SPI chapter.
+ * @cs_gpio: CS line status, 'true' if CS line is asserted by gpio.
+ * 'false' if asserted by internal dedicated pin.
* @line: Custom 'identity' of the CS line.
*
* This is per SPI-Slave Chipselect information.
@@ -25,6 +27,7 @@ struct platform_device;
*/
struct s3c64xx_spi_csinfo {
u8 fb_delay;
+ bool cs_gpio;
unsigned line;
};
--
1.7.10.4
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