[PATCH v4 3/5] gpio: raspberrypi-exp: Driver for RPi3 GPIO expander via mailbox service
Baruch Siach
baruch at tkos.co.il
Wed Feb 7 10:35:24 PST 2018
From: Dave Stevenson <dave.stevenson at raspberrypi.org>
Pi3 and Compute Module 3 have a GPIO expander that the
VPU communicates with.
There is a mailbox service that now allows control of this
expander, so add a kernel driver that can make use of it.
Reviewed-by: Stefan Wahren <stefan.wahren at i2se.com>
Signed-off-by: Dave Stevenson <dave.stevenson at raspberrypi.org>
Signed-off-by: Baruch Siach <baruch at tkos.co.il>
---
v4:
* Don't set the .owner driver field
* Add Stefan's review tag
v3:
* Tweak Kconfig driver prompt
* Make GPIO_RASPBERRYPI_EXP tristate
* Make COMPILE_TEST independent of RASPBERRYPI_FIRMWARE
* Remove redundant DMA header
* Use less code lines for dev_err()
* Check rpi_exp_gpio_get_polarity() return value
* Remove redundant platform_set_drvdata() call
v2:
* Rename driver to gpio-raspberrypi-exp
* Populate the gpiochip parent device pointer
* Use macro for the mailbox base GPIO number
* Drop linux/gpio.h and GPIOF_DIR_*
* Check and print firmware error value
* Use devm_gpiochip_add_data(); drop .remove
* A few more minor tweaks
---
drivers/gpio/Kconfig | 9 ++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-raspberrypi-exp.c | 252 ++++++++++++++++++++++++++++++++++++
3 files changed, 262 insertions(+)
create mode 100644 drivers/gpio/gpio-raspberrypi-exp.c
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 8dbb2280538d..fd0562a37f68 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -122,6 +122,15 @@ config GPIO_ATH79
Select this option to enable GPIO driver for
Atheros AR71XX/AR724X/AR913X SoC devices.
+config GPIO_RASPBERRYPI_EXP
+ tristate "Raspberry Pi 3 GPIO Expander"
+ default RASPBERRYPI_FIRMWARE
+ depends on OF_GPIO
+ depends on (ARCH_BCM2835 && RASPBERRYPI_FIRMWARE) || COMPILE_TEST
+ help
+ Turn on GPIO support for the expander on Raspberry Pi 3 boards, using
+ the firmware mailbox to communicate with VideoCore on BCM283x chips.
+
config GPIO_BCM_KONA
bool "Broadcom Kona GPIO"
depends on OF_GPIO && (ARCH_BCM_MOBILE || COMPILE_TEST)
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index cccb0d40846c..76dc0a02bd56 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_GPIO_AMDPT) += gpio-amdpt.o
obj-$(CONFIG_GPIO_ARIZONA) += gpio-arizona.o
obj-$(CONFIG_GPIO_ATH79) += gpio-ath79.o
obj-$(CONFIG_GPIO_ASPEED) += gpio-aspeed.o
+obj-$(CONFIG_GPIO_RASPBERRYPI_EXP) += gpio-raspberrypi-exp.o
obj-$(CONFIG_GPIO_BCM_KONA) += gpio-bcm-kona.o
obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd9571mwv.o
obj-$(CONFIG_GPIO_BRCMSTB) += gpio-brcmstb.o
diff --git a/drivers/gpio/gpio-raspberrypi-exp.c b/drivers/gpio/gpio-raspberrypi-exp.c
new file mode 100644
index 000000000000..215ba0362971
--- /dev/null
+++ b/drivers/gpio/gpio-raspberrypi-exp.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Raspberry Pi 3 expander GPIO driver
+ *
+ * Uses the firmware mailbox service to communicate with the
+ * GPIO expander on the VPU.
+ *
+ * Copyright (C) 2017 Raspberry Pi Trading Ltd.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define MODULE_NAME "raspberrypi-exp-gpio"
+#define NUM_GPIO 8
+
+#define RPI_EXP_GPIO_BASE 128
+
+#define RPI_EXP_GPIO_DIR_IN 0
+#define RPI_EXP_GPIO_DIR_OUT 1
+
+struct rpi_exp_gpio {
+ struct gpio_chip gc;
+ struct rpi_firmware *fw;
+};
+
+/* VC4 firmware mailbox interface data structures */
+
+struct gpio_set_config {
+ u32 gpio;
+ u32 direction;
+ u32 polarity;
+ u32 term_en;
+ u32 term_pull_up;
+ u32 state;
+};
+
+struct gpio_get_config {
+ u32 gpio;
+ u32 direction;
+ u32 polarity;
+ u32 term_en;
+ u32 term_pull_up;
+};
+
+struct gpio_get_set_state {
+ u32 gpio;
+ u32 state;
+};
+
+static int rpi_exp_gpio_get_polarity(struct gpio_chip *gc, unsigned int off)
+{
+ struct rpi_exp_gpio *gpio;
+ struct gpio_get_config get;
+ int ret;
+
+ gpio = gpiochip_get_data(gc);
+
+ get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
+
+ ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
+ &get, sizeof(get));
+ if (ret || get.gpio != 0) {
+ dev_err(gc->parent, "Failed to get GPIO %u config (%d %x)\n",
+ off, ret, get.gpio);
+ return ret ? ret : -EIO;
+ }
+ return get.polarity;
+}
+
+static int rpi_exp_gpio_dir_in(struct gpio_chip *gc, unsigned int off)
+{
+ struct rpi_exp_gpio *gpio;
+ struct gpio_set_config set_in;
+ int ret;
+
+ gpio = gpiochip_get_data(gc);
+
+ set_in.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
+ set_in.direction = RPI_EXP_GPIO_DIR_IN;
+ set_in.term_en = 0; /* termination disabled */
+ set_in.term_pull_up = 0; /* n/a as termination disabled */
+ set_in.state = 0; /* n/a as configured as an input */
+
+ ret = rpi_exp_gpio_get_polarity(gc, off);
+ if (ret < 0)
+ return ret;
+ set_in.polarity = ret; /* Retain existing setting */
+
+ ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
+ &set_in, sizeof(set_in));
+ if (ret || set_in.gpio != 0) {
+ dev_err(gc->parent, "Failed to set GPIO %u to input (%d %x)\n",
+ off, ret, set_in.gpio);
+ return ret ? ret : -EIO;
+ }
+ return 0;
+}
+
+static int rpi_exp_gpio_dir_out(struct gpio_chip *gc, unsigned int off, int val)
+{
+ struct rpi_exp_gpio *gpio;
+ struct gpio_set_config set_out;
+ int ret;
+
+ gpio = gpiochip_get_data(gc);
+
+ set_out.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
+ set_out.direction = RPI_EXP_GPIO_DIR_OUT;
+ set_out.term_en = 0; /* n/a as an output */
+ set_out.term_pull_up = 0; /* n/a as termination disabled */
+ set_out.state = val; /* Output state */
+
+ ret = rpi_exp_gpio_get_polarity(gc, off);
+ if (ret < 0)
+ return ret;
+ set_out.polarity = ret; /* Retain existing setting */
+
+ ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
+ &set_out, sizeof(set_out));
+ if (ret || set_out.gpio != 0) {
+ dev_err(gc->parent, "Failed to set GPIO %u to output (%d %x)\n",
+ off, ret, set_out.gpio);
+ return ret ? ret : -EIO;
+ }
+ return 0;
+}
+
+static int rpi_exp_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
+{
+ struct rpi_exp_gpio *gpio;
+ struct gpio_get_config get;
+ int ret;
+
+ gpio = gpiochip_get_data(gc);
+
+ get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
+
+ ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
+ &get, sizeof(get));
+ if (ret || get.gpio != 0) {
+ dev_err(gc->parent,
+ "Failed to get GPIO %u config (%d %x)\n", off, ret,
+ get.gpio);
+ return ret ? ret : -EIO;
+ }
+ return !get.direction;
+}
+
+static int rpi_exp_gpio_get(struct gpio_chip *gc, unsigned int off)
+{
+ struct rpi_exp_gpio *gpio;
+ struct gpio_get_set_state get;
+ int ret;
+
+ gpio = gpiochip_get_data(gc);
+
+ get.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
+ get.state = 0; /* storage for returned value */
+
+ ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_STATE,
+ &get, sizeof(get));
+ if (ret || get.gpio != 0) {
+ dev_err(gc->parent,
+ "Failed to get GPIO %u state (%d %x)\n", off, ret,
+ get.gpio);
+ return ret ? ret : -EIO;
+ }
+ return !!get.state;
+}
+
+static void rpi_exp_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
+{
+ struct rpi_exp_gpio *gpio;
+ struct gpio_get_set_state set;
+ int ret;
+
+ gpio = gpiochip_get_data(gc);
+
+ set.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
+ set.state = val; /* Output state */
+
+ ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_STATE,
+ &set, sizeof(set));
+ if (ret || set.gpio != 0)
+ dev_err(gc->parent,
+ "Failed to set GPIO %u state (%d %x)\n", off, ret,
+ set.gpio);
+}
+
+static int rpi_exp_gpio_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct device_node *fw_node;
+ struct rpi_firmware *fw;
+ struct rpi_exp_gpio *rpi_gpio;
+
+ fw_node = of_parse_phandle(np, "firmware", 0);
+ if (!fw_node) {
+ dev_err(dev, "Missing firmware node\n");
+ return -ENOENT;
+ }
+
+ fw = rpi_firmware_get(fw_node);
+ if (!fw)
+ return -EPROBE_DEFER;
+
+ rpi_gpio = devm_kzalloc(dev, sizeof(*rpi_gpio), GFP_KERNEL);
+ if (!rpi_gpio)
+ return -ENOMEM;
+
+ rpi_gpio->fw = fw;
+ rpi_gpio->gc.parent = dev;
+ rpi_gpio->gc.label = MODULE_NAME;
+ rpi_gpio->gc.owner = THIS_MODULE;
+ rpi_gpio->gc.of_node = np;
+ rpi_gpio->gc.base = -1;
+ rpi_gpio->gc.ngpio = NUM_GPIO;
+
+ rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
+ rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
+ rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
+ rpi_gpio->gc.get = rpi_exp_gpio_get;
+ rpi_gpio->gc.set = rpi_exp_gpio_set;
+ rpi_gpio->gc.can_sleep = true;
+
+ return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
+}
+
+static const struct of_device_id rpi_exp_gpio_ids[] = {
+ { .compatible = "raspberrypi,firmware-gpio" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
+
+static struct platform_driver rpi_exp_gpio_driver = {
+ .driver = {
+ .name = MODULE_NAME,
+ .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
+ },
+ .probe = rpi_exp_gpio_probe,
+};
+module_platform_driver(rpi_exp_gpio_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dave Stevenson <dave.stevenson at raspberrypi.org>");
+MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
+MODULE_ALIAS("platform:rpi-exp-gpio");
--
2.15.1
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