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-rw-r--r--drivers/spi/spi.c104
-rw-r--r--include/linux/spi/spi.h23
2 files changed, 113 insertions, 14 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 9a7def7c3237..13f447a67d67 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 +776,20 @@ 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(spi->cs_gpiod, !enable);
+ else
+ gpio_set_value(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 +1629,21 @@ 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 +2159,60 @@ 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 +2275,16 @@ 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;
+ } 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 +2998,7 @@ 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;
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 314d922ca607..916bba47d156 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -12,6 +12,7 @@
#include <linux/kthread.h>
#include <linux/completion.h>
#include <linux/scatterlist.h>
+#include <linux/gpio/consumer.h>
struct dma_chan;
struct property_entry;
@@ -116,7 +117,10 @@ void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
* @modalias: Name of the driver to use with this device, or an alias
* for that name. This appears in the sysfs "modalias" attribute
* for driver coldplugging, and in uevents used for hotplugging
- * @cs_gpio: gpio number of the chipselect line (optional, -ENOENT when
+ * @cs_gpio: LEGACY: gpio number of the chipselect line (optional, -ENOENT when
+ * not using a GPIO line) use cs_gpiod in new drivers by opting in on
+ * the spi_master.
+ * @cs_gpiod: gpio descriptor of the chipselect line (optional, NULL when
* not using a GPIO line)
*
* @statistics: statistics for the spi_device
@@ -163,7 +167,8 @@ struct spi_device {
void *controller_data;
char modalias[SPI_NAME_SIZE];
const char *driver_override;
- int cs_gpio; /* chip select gpio */
+ int cs_gpio; /* LEGACY: chip select gpio */
+ struct gpio_desc *cs_gpiod; /* chip select gpio desc */
/* the statistics */
struct spi_statistics statistics;
@@ -376,9 +381,17 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
* controller has native support for memory like operations.
* @unprepare_message: undo any work done by prepare_message().
* @slave_abort: abort the ongoing transfer request on an SPI slave controller
- * @cs_gpios: Array of GPIOs to use as chip select lines; one per CS
- * number. Any individual value may be -ENOENT for CS lines that
+ * @cs_gpios: LEGACY: array of GPIO descs to use as chip select lines; one per
+ * CS number. Any individual value may be -ENOENT for CS lines that
+ * are not GPIOs (driven by the SPI controller itself). Use the cs_gpiods
+ * in new drivers.
+ * @cs_gpiods: Array of GPIO descs to use as chip select lines; one per CS
+ * number. Any individual value may be NULL for CS lines that
* are not GPIOs (driven by the SPI controller itself).
+ * @use_gpio_descriptors: Turns on the code in the SPI core to parse and grab
+ * GPIO descriptors rather than using global GPIO numbers grabbed by the
+ * driver. This will fill in @cs_gpiods and @cs_gpios should not be used,
+ * and SPI devices will have the cs_gpiod assigned rather than cs_gpio.
* @statistics: statistics for the spi_controller
* @dma_tx: DMA transmit channel
* @dma_rx: DMA receive channel
@@ -557,6 +570,8 @@ struct spi_controller {
/* gpio chip select */
int *cs_gpios;
+ struct gpio_desc **cs_gpiods;
+ bool use_gpio_descriptors;
/* statistics */
struct spi_statistics statistics;
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.