summaryrefslogtreecommitdiff
path: root/drivers/spi/spi.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/spi/spi.c')
-rw-r--r--drivers/spi/spi.c115
1 files changed, 105 insertions, 10 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 9a7def7c3237..93986f879b09 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -19,6 +19,7 @@
#include <linux/spi/spi.h>
#include <linux/spi/spi-mem.h>
#include <linux/of_gpio.h>
+#include <linux/gpio/consumer.h>
#include <linux/pm_runtime.h>
#include <linux/pm_domain.h>
#include <linux/property.h>
@@ -578,7 +579,10 @@ int spi_add_device(struct spi_device *spi)
goto done;
}
- if (ctlr->cs_gpios)
+ /* Descriptors take precedence */
+ if (ctlr->cs_gpiods)
+ spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
+ else if (ctlr->cs_gpios)
spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];
/* Drivers may modify this initial i/o setup, but will
@@ -772,10 +776,21 @@ static void spi_set_cs(struct spi_device *spi, bool enable)
if (spi->mode & SPI_CS_HIGH)
enable = !enable;
- if (gpio_is_valid(spi->cs_gpio)) {
- /* Honour the SPI_NO_CS flag */
- if (!(spi->mode & SPI_NO_CS))
- gpio_set_value(spi->cs_gpio, !enable);
+ if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
+ /*
+ * Honour the SPI_NO_CS flag and invert the enable line, as
+ * active low is default for SPI. Execution paths that handle
+ * polarity inversion in gpiolib (such as device tree) will
+ * enforce active high using the SPI_CS_HIGH resulting in a
+ * double inversion through the code above.
+ */
+ if (!(spi->mode & SPI_NO_CS)) {
+ if (spi->cs_gpiod)
+ gpiod_set_value_cansleep(spi->cs_gpiod,
+ !enable);
+ else
+ gpio_set_value_cansleep(spi->cs_gpio, !enable);
+ }
/* Some SPI masters need both GPIO CS & slave_select */
if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
spi->controller->set_cs)
@@ -1615,13 +1630,21 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
spi->mode |= SPI_CPHA;
if (of_property_read_bool(nc, "spi-cpol"))
spi->mode |= SPI_CPOL;
- if (of_property_read_bool(nc, "spi-cs-high"))
- spi->mode |= SPI_CS_HIGH;
if (of_property_read_bool(nc, "spi-3wire"))
spi->mode |= SPI_3WIRE;
if (of_property_read_bool(nc, "spi-lsb-first"))
spi->mode |= SPI_LSB_FIRST;
+ /*
+ * For descriptors associated with the device, polarity inversion is
+ * handled in the gpiolib, so all chip selects are "active high" in
+ * the logical sense, the gpiolib will invert the line if need be.
+ */
+ if (ctlr->use_gpio_descriptors)
+ spi->mode |= SPI_CS_HIGH;
+ else if (of_property_read_bool(nc, "spi-cs-high"))
+ spi->mode |= SPI_CS_HIGH;
+
/* Device DUAL/QUAD mode */
if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
switch (value) {
@@ -2137,6 +2160,60 @@ static int of_spi_register_master(struct spi_controller *ctlr)
}
#endif
+/**
+ * spi_get_gpio_descs() - grab chip select GPIOs for the master
+ * @ctlr: The SPI master to grab GPIO descriptors for
+ */
+static int spi_get_gpio_descs(struct spi_controller *ctlr)
+{
+ int nb, i;
+ struct gpio_desc **cs;
+ struct device *dev = &ctlr->dev;
+
+ nb = gpiod_count(dev, "cs");
+ ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
+
+ /* No GPIOs at all is fine, else return the error */
+ if (nb == 0 || nb == -ENOENT)
+ return 0;
+ else if (nb < 0)
+ return nb;
+
+ cs = devm_kcalloc(dev, ctlr->num_chipselect, sizeof(*cs),
+ GFP_KERNEL);
+ if (!cs)
+ return -ENOMEM;
+ ctlr->cs_gpiods = cs;
+
+ for (i = 0; i < nb; i++) {
+ /*
+ * Most chipselects are active low, the inverted
+ * semantics are handled by special quirks in gpiolib,
+ * so initializing them GPIOD_OUT_LOW here means
+ * "unasserted", in most cases this will drive the physical
+ * line high.
+ */
+ cs[i] = devm_gpiod_get_index_optional(dev, "cs", i,
+ GPIOD_OUT_LOW);
+
+ if (cs[i]) {
+ /*
+ * If we find a CS GPIO, name it after the device and
+ * chip select line.
+ */
+ char *gpioname;
+
+ gpioname = devm_kasprintf(dev, GFP_KERNEL, "%s CS%d",
+ dev_name(dev), i);
+ if (!gpioname)
+ return -ENOMEM;
+ gpiod_set_consumer_name(cs[i], gpioname);
+ }
+ }
+
+ return 0;
+}
+
static int spi_controller_check_ops(struct spi_controller *ctlr)
{
/*
@@ -2199,9 +2276,21 @@ int spi_register_controller(struct spi_controller *ctlr)
return status;
if (!spi_controller_is_slave(ctlr)) {
- status = of_spi_register_master(ctlr);
- if (status)
- return status;
+ if (ctlr->use_gpio_descriptors) {
+ status = spi_get_gpio_descs(ctlr);
+ if (status)
+ return status;
+ /*
+ * A controller using GPIO descriptors always
+ * supports SPI_CS_HIGH if need be.
+ */
+ ctlr->mode_bits |= SPI_CS_HIGH;
+ } else {
+ /* Legacy code path for GPIOs from DT */
+ status = of_spi_register_master(ctlr);
+ if (status)
+ return status;
+ }
}
/* even if it's just one always-selected device, there must
@@ -2915,6 +3004,7 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
* cs_change is set for each transfer.
*/
if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
+ spi->cs_gpiod ||
gpio_is_valid(spi->cs_gpio))) {
size_t maxsize;
int ret;
@@ -2961,6 +3051,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
* it is not set for this transfer.
* Set transfer tx_nbits and rx_nbits as single transfer default
* (SPI_NBITS_SINGLE) if it is not set for this transfer.
+ * Ensure transfer word_delay is at least as long as that required by
+ * device itself.
*/
message->frame_length = 0;
list_for_each_entry(xfer, &message->transfers, transfer_list) {
@@ -3031,6 +3123,9 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
!(spi->mode & SPI_RX_QUAD))
return -EINVAL;
}
+
+ if (xfer->word_delay_usecs < spi->word_delay_usecs)
+ xfer->word_delay_usecs = spi->word_delay_usecs;
}
message->status = -EINPROGRESS;