gpio: raspberrypi-exp: Driver for RPi3 GPIO expander via mailbox service

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@i2se.com>
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 8dbb228..fd0562a 100644 (file)
--- 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 cccb0d4..76dc0a0 100644 (file)
--- 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 (file)
index 0000000..d6d36d5
--- /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_get_parent(np);
+       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@raspberrypi.org>");
+MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
+MODULE_ALIAS("platform:rpi-exp-gpio");