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path: root/drivers/spi/spi-gpio.c
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Diffstat (limited to 'drivers/spi/spi-gpio.c')
-rw-r--r--drivers/spi/spi-gpio.c270
1 files changed, 92 insertions, 178 deletions
diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
index 1c34c9314c8a..b85a93cad44a 100644
--- a/drivers/spi/spi-gpio.c
+++ b/drivers/spi/spi-gpio.c
@@ -2,6 +2,7 @@
* SPI master driver using generic bitbanged GPIO
*
* Copyright (C) 2006,2008 David Brownell
+ * Copyright (C) 2017 Linus Walleij
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -16,10 +17,9 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/of_device.h>
-#include <linux/of_gpio.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
@@ -44,7 +44,11 @@ struct spi_gpio {
struct spi_bitbang bitbang;
struct spi_gpio_platform_data pdata;
struct platform_device *pdev;
- unsigned long cs_gpios[0];
+ struct gpio_desc *sck;
+ struct gpio_desc *miso;
+ struct gpio_desc *mosi;
+ struct gpio_desc **cs_gpios;
+ bool has_cs;
};
/*----------------------------------------------------------------------*/
@@ -77,13 +81,6 @@ struct spi_gpio {
#define GENERIC_BITBANG /* vs tight inlines */
-/* all functions referencing these symbols must define pdata */
-#define SPI_MISO_GPIO ((pdata)->miso)
-#define SPI_MOSI_GPIO ((pdata)->mosi)
-#define SPI_SCK_GPIO ((pdata)->sck)
-
-#define SPI_N_CHIPSEL ((pdata)->num_chipselect)
-
#endif
/*----------------------------------------------------------------------*/
@@ -105,25 +102,27 @@ spi_to_pdata(const struct spi_device *spi)
return &spi_to_spi_gpio(spi)->pdata;
}
-/* this is #defined to avoid unused-variable warnings when inlining */
-#define pdata spi_to_pdata(spi)
-
+/* These helpers are in turn called by the bitbang inlines */
static inline void setsck(const struct spi_device *spi, int is_on)
{
- gpio_set_value_cansleep(SPI_SCK_GPIO, is_on);
+ struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+ gpiod_set_value_cansleep(spi_gpio->sck, is_on);
}
static inline void setmosi(const struct spi_device *spi, int is_on)
{
- gpio_set_value_cansleep(SPI_MOSI_GPIO, is_on);
+ struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+ gpiod_set_value_cansleep(spi_gpio->mosi, is_on);
}
static inline int getmiso(const struct spi_device *spi)
{
- return !!gpio_get_value_cansleep(SPI_MISO_GPIO);
-}
+ struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
-#undef pdata
+ return !!gpiod_get_value_cansleep(spi_gpio->miso);
+}
/*
* NOTE: this clocks "as fast as we can". It "should" be a function of the
@@ -216,123 +215,89 @@ static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
{
struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
- unsigned long cs = spi_gpio->cs_gpios[spi->chip_select];
- /* set initial clock polarity */
+ /* set initial clock line level */
if (is_active)
- setsck(spi, spi->mode & SPI_CPOL);
+ gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
+
+ /* Drive chip select line, if we have one */
+ if (spi_gpio->has_cs) {
+ struct gpio_desc *cs = spi_gpio->cs_gpios[spi->chip_select];
- if (cs != SPI_GPIO_NO_CHIPSELECT) {
- /* SPI is normally active-low */
- gpio_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
+ /* SPI chip selects are normally active-low */
+ gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
}
}
static int spi_gpio_setup(struct spi_device *spi)
{
- unsigned long cs;
+ struct gpio_desc *cs;
int status = 0;
struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
- struct device_node *np = spi->master->dev.of_node;
-
- if (np) {
- /*
- * In DT environments, the CS GPIOs have already been
- * initialized from the "cs-gpios" property of the node.
- */
- cs = spi_gpio->cs_gpios[spi->chip_select];
- } else {
- /*
- * ... otherwise, take it from spi->controller_data
- */
- cs = (uintptr_t) spi->controller_data;
- }
- if (!spi->controller_state) {
- if (cs != SPI_GPIO_NO_CHIPSELECT) {
- status = gpio_request(cs, dev_name(&spi->dev));
- if (status)
- return status;
- status = gpio_direction_output(cs,
- !(spi->mode & SPI_CS_HIGH));
- }
- }
- if (!status) {
- /* in case it was initialized from static board data */
- spi_gpio->cs_gpios[spi->chip_select] = cs;
+ /*
+ * The CS GPIOs have already been
+ * initialized from the descriptor lookup.
+ */
+ cs = spi_gpio->cs_gpios[spi->chip_select];
+ if (!spi->controller_state && cs)
+ status = gpiod_direction_output(cs,
+ !(spi->mode & SPI_CS_HIGH));
+
+ if (!status)
status = spi_bitbang_setup(spi);
- }
- if (status) {
- if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
- gpio_free(cs);
- }
return status;
}
static void spi_gpio_cleanup(struct spi_device *spi)
{
- struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
- unsigned long cs = spi_gpio->cs_gpios[spi->chip_select];
-
- if (cs != SPI_GPIO_NO_CHIPSELECT)
- gpio_free(cs);
spi_bitbang_cleanup(spi);
}
-static int spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
-{
- int value;
-
- value = gpio_request(pin, label);
- if (value == 0) {
- if (is_in)
- value = gpio_direction_input(pin);
- else
- value = gpio_direction_output(pin, 0);
- }
- return value;
-}
-
-static int spi_gpio_request(struct spi_gpio_platform_data *pdata,
- const char *label, u16 *res_flags)
+/*
+ * It can be convenient to use this driver with pins that have alternate
+ * functions associated with a "native" SPI controller if a driver for that
+ * controller is not available, or is missing important functionality.
+ *
+ * On platforms which can do so, configure MISO with a weak pullup unless
+ * there's an external pullup on that signal. That saves power by avoiding
+ * floating signals. (A weak pulldown would save power too, but many
+ * drivers expect to see all-ones data as the no slave "response".)
+ */
+static int spi_gpio_request(struct device *dev,
+ struct spi_gpio *spi_gpio,
+ unsigned int num_chipselects,
+ u16 *mflags)
{
- int value;
-
- /* NOTE: SPI_*_GPIO symbols may reference "pdata" */
+ int i;
- if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
- value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
- if (value)
- goto done;
- } else {
+ spi_gpio->mosi = devm_gpiod_get_optional(dev, "mosi", GPIOD_OUT_LOW);
+ if (IS_ERR(spi_gpio->mosi))
+ return PTR_ERR(spi_gpio->mosi);
+ if (!spi_gpio->mosi)
/* HW configuration without MOSI pin */
- *res_flags |= SPI_MASTER_NO_TX;
- }
+ *mflags |= SPI_MASTER_NO_TX;
- if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
- value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
- if (value)
- goto free_mosi;
- } else {
+ spi_gpio->miso = devm_gpiod_get_optional(dev, "miso", GPIOD_IN);
+ if (IS_ERR(spi_gpio->miso))
+ return PTR_ERR(spi_gpio->miso);
+ if (!spi_gpio->miso)
/* HW configuration without MISO pin */
- *res_flags |= SPI_MASTER_NO_RX;
- }
+ *mflags |= SPI_MASTER_NO_RX;
- value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
- if (value)
- goto free_miso;
+ spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);
+ if (IS_ERR(spi_gpio->mosi))
+ return PTR_ERR(spi_gpio->mosi);
- goto done;
+ for (i = 0; i < num_chipselects; i++) {
+ spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs",
+ i, GPIOD_OUT_HIGH);
+ if (IS_ERR(spi_gpio->cs_gpios[i]))
+ return PTR_ERR(spi_gpio->cs_gpios[i]);
+ }
-free_miso:
- if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
- gpio_free(SPI_MISO_GPIO);
-free_mosi:
- if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
- gpio_free(SPI_MOSI_GPIO);
-done:
- return value;
+ return 0;
}
#ifdef CONFIG_OF
@@ -358,26 +323,6 @@ static int spi_gpio_probe_dt(struct platform_device *pdev)
if (!pdata)
return -ENOMEM;
- ret = of_get_named_gpio(np, "gpio-sck", 0);
- if (ret < 0) {
- dev_err(&pdev->dev, "gpio-sck property not found\n");
- goto error_free;
- }
- pdata->sck = ret;
-
- ret = of_get_named_gpio(np, "gpio-miso", 0);
- if (ret < 0) {
- dev_info(&pdev->dev, "gpio-miso property not found, switching to no-rx mode\n");
- pdata->miso = SPI_GPIO_NO_MISO;
- } else
- pdata->miso = ret;
-
- ret = of_get_named_gpio(np, "gpio-mosi", 0);
- if (ret < 0) {
- dev_info(&pdev->dev, "gpio-mosi property not found, switching to no-tx mode\n");
- pdata->mosi = SPI_GPIO_NO_MOSI;
- } else
- pdata->mosi = ret;
ret = of_property_read_u32(np, "num-chipselects", &tmp);
if (ret < 0) {
@@ -409,7 +354,6 @@ static int spi_gpio_probe(struct platform_device *pdev)
struct spi_gpio_platform_data *pdata;
u16 master_flags = 0;
bool use_of = 0;
- int num_devices;
status = spi_gpio_probe_dt(pdev);
if (status < 0)
@@ -423,59 +367,41 @@ static int spi_gpio_probe(struct platform_device *pdev)
return -ENODEV;
#endif
- if (use_of && !SPI_N_CHIPSEL)
- num_devices = 1;
- else
- num_devices = SPI_N_CHIPSEL;
-
- status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags);
- if (status < 0)
- return status;
+ master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio));
+ if (!master)
+ return -ENOMEM;
- master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio) +
- (sizeof(unsigned long) * num_devices));
- if (!master) {
- status = -ENOMEM;
- goto gpio_free;
- }
spi_gpio = spi_master_get_devdata(master);
+
+ spi_gpio->cs_gpios = devm_kzalloc(&pdev->dev,
+ pdata->num_chipselect * sizeof(*spi_gpio->cs_gpios),
+ GFP_KERNEL);
+ if (!spi_gpio->cs_gpios)
+ return -ENOMEM;
+
platform_set_drvdata(pdev, spi_gpio);
+ /* Determine if we have chip selects connected */
+ spi_gpio->has_cs = !!pdata->num_chipselect;
+
spi_gpio->pdev = pdev;
if (pdata)
spi_gpio->pdata = *pdata;
+ status = spi_gpio_request(&pdev->dev, spi_gpio,
+ pdata->num_chipselect, &master_flags);
+ if (status)
+ return status;
+
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
master->flags = master_flags;
master->bus_num = pdev->id;
- master->num_chipselect = num_devices;
+ /* The master needs to think there is a chipselect even if not connected */
+ master->num_chipselect = spi_gpio->has_cs ? pdata->num_chipselect : 1;
master->setup = spi_gpio_setup;
master->cleanup = spi_gpio_cleanup;
#ifdef CONFIG_OF
master->dev.of_node = pdev->dev.of_node;
-
- if (use_of) {
- int i;
- struct device_node *np = pdev->dev.of_node;
-
- /*
- * In DT environments, take the CS GPIO from the "cs-gpios"
- * property of the node.
- */
-
- if (!SPI_N_CHIPSEL)
- spi_gpio->cs_gpios[0] = SPI_GPIO_NO_CHIPSELECT;
- else
- for (i = 0; i < SPI_N_CHIPSEL; i++) {
- status = of_get_named_gpio(np, "cs-gpios", i);
- if (status < 0) {
- dev_err(&pdev->dev,
- "invalid cs-gpios property\n");
- goto gpio_free;
- }
- spi_gpio->cs_gpios[i] = status;
- }
- }
#endif
spi_gpio->bitbang.master = master;
@@ -496,15 +422,8 @@ static int spi_gpio_probe(struct platform_device *pdev)
spi_gpio->bitbang.flags = SPI_CS_HIGH;
status = spi_bitbang_start(&spi_gpio->bitbang);
- if (status < 0) {
-gpio_free:
- if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
- gpio_free(SPI_MISO_GPIO);
- if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
- gpio_free(SPI_MOSI_GPIO);
- gpio_free(SPI_SCK_GPIO);
+ if (status)
spi_master_put(master);
- }
return status;
}
@@ -520,11 +439,6 @@ static int spi_gpio_remove(struct platform_device *pdev)
/* stop() unregisters child devices too */
spi_bitbang_stop(&spi_gpio->bitbang);
- if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
- gpio_free(SPI_MISO_GPIO);
- if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
- gpio_free(SPI_MOSI_GPIO);
- gpio_free(SPI_SCK_GPIO);
spi_master_put(spi_gpio->bitbang.master);
return 0;