LXR linux/drivers/gpio/gpio-raspberrypi-exp.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 *  Raspberry Pi 3 expander GPIO driver
   4 *
   5 *  Uses the firmware mailbox service to communicate with the
   6 *  GPIO expander on the VPU.
   7 *
   8 *  Copyright (C) 2017 Raspberry Pi Trading Ltd.
   9 */
  10
  11#include <linux/err.h>
  12#include <linux/gpio/driver.h>
  13#include <linux/module.h>
  14#include <linux/platform_device.h>
  15#include <soc/bcm2835/raspberrypi-firmware.h>
  16
  17#define MODULE_NAME "raspberrypi-exp-gpio"
  18#define NUM_GPIO 8
  19
  20#define RPI_EXP_GPIO_BASE       128
  21
  22#define RPI_EXP_GPIO_DIR_IN     0
  23#define RPI_EXP_GPIO_DIR_OUT    1
  24
  25struct rpi_exp_gpio {
  26        struct gpio_chip gc;
  27        struct rpi_firmware *fw;
  28};
  29
  30/* VC4 firmware mailbox interface data structures */
  31
  32struct gpio_set_config {
  33        u32 gpio;
  34        u32 direction;
  35        u32 polarity;
  36        u32 term_en;
  37        u32 term_pull_up;
  38        u32 state;
  39};
  40
  41struct gpio_get_config {
  42        u32 gpio;
  43        u32 direction;
  44        u32 polarity;
  45        u32 term_en;
  46        u32 term_pull_up;
  47};
  48
  49struct gpio_get_set_state {
  50        u32 gpio;
  51        u32 state;
  52};
  53
  54static int rpi_exp_gpio_get_polarity(struct gpio_chip *gc, unsigned int off)
  55{
  56        struct rpi_exp_gpio *gpio;
  57        struct gpio_get_config get;
  58        int ret;
  59
  60        gpio = gpiochip_get_data(gc);
  61
  62        get.gpio = off + RPI_EXP_GPIO_BASE;     /* GPIO to update */
  63
  64        ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
  65                                    &get, sizeof(get));
  66        if (ret || get.gpio != 0) {
  67                dev_err(gc->parent, "Failed to get GPIO %u config (%d %x)\n",
  68                        off, ret, get.gpio);
  69                return ret ? ret : -EIO;
  70        }
  71        return get.polarity;
  72}
  73
  74static int rpi_exp_gpio_dir_in(struct gpio_chip *gc, unsigned int off)
  75{
  76        struct rpi_exp_gpio *gpio;
  77        struct gpio_set_config set_in;
  78        int ret;
  79
  80        gpio = gpiochip_get_data(gc);
  81
  82        set_in.gpio = off + RPI_EXP_GPIO_BASE;  /* GPIO to update */
  83        set_in.direction = RPI_EXP_GPIO_DIR_IN;
  84        set_in.term_en = 0;             /* termination disabled */
  85        set_in.term_pull_up = 0;        /* n/a as termination disabled */
  86        set_in.state = 0;               /* n/a as configured as an input */
  87
  88        ret = rpi_exp_gpio_get_polarity(gc, off);
  89        if (ret < 0)
  90                return ret;
  91        set_in.polarity = ret;          /* Retain existing setting */
  92
  93        ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
  94                                    &set_in, sizeof(set_in));
  95        if (ret || set_in.gpio != 0) {
  96                dev_err(gc->parent, "Failed to set GPIO %u to input (%d %x)\n",
  97                        off, ret, set_in.gpio);
  98                return ret ? ret : -EIO;
  99        }
 100        return 0;
 101}
 102
 103static int rpi_exp_gpio_dir_out(struct gpio_chip *gc, unsigned int off, int val)
 104{
 105        struct rpi_exp_gpio *gpio;
 106        struct gpio_set_config set_out;
 107        int ret;
 108
 109        gpio = gpiochip_get_data(gc);
 110
 111        set_out.gpio = off + RPI_EXP_GPIO_BASE; /* GPIO to update */
 112        set_out.direction = RPI_EXP_GPIO_DIR_OUT;
 113        set_out.term_en = 0;            /* n/a as an output */
 114        set_out.term_pull_up = 0;       /* n/a as termination disabled */
 115        set_out.state = val;            /* Output state */
 116
 117        ret = rpi_exp_gpio_get_polarity(gc, off);
 118        if (ret < 0)
 119                return ret;
 120        set_out.polarity = ret;         /* Retain existing setting */
 121
 122        ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_CONFIG,
 123                                    &set_out, sizeof(set_out));
 124        if (ret || set_out.gpio != 0) {
 125                dev_err(gc->parent, "Failed to set GPIO %u to output (%d %x)\n",
 126                        off, ret, set_out.gpio);
 127                return ret ? ret : -EIO;
 128        }
 129        return 0;
 130}
 131
 132static int rpi_exp_gpio_get_direction(struct gpio_chip *gc, unsigned int off)
 133{
 134        struct rpi_exp_gpio *gpio;
 135        struct gpio_get_config get;
 136        int ret;
 137
 138        gpio = gpiochip_get_data(gc);
 139
 140        get.gpio = off + RPI_EXP_GPIO_BASE;     /* GPIO to update */
 141
 142        ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_CONFIG,
 143                                    &get, sizeof(get));
 144        if (ret || get.gpio != 0) {
 145                dev_err(gc->parent,
 146                        "Failed to get GPIO %u config (%d %x)\n", off, ret,
 147                        get.gpio);
 148                return ret ? ret : -EIO;
 149        }
 150        if (get.direction)
 151                return GPIO_LINE_DIRECTION_OUT;
 152
 153        return GPIO_LINE_DIRECTION_IN;
 154}
 155
 156static int rpi_exp_gpio_get(struct gpio_chip *gc, unsigned int off)
 157{
 158        struct rpi_exp_gpio *gpio;
 159        struct gpio_get_set_state get;
 160        int ret;
 161
 162        gpio = gpiochip_get_data(gc);
 163
 164        get.gpio = off + RPI_EXP_GPIO_BASE;     /* GPIO to update */
 165        get.state = 0;          /* storage for returned value */
 166
 167        ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_GET_GPIO_STATE,
 168                                         &get, sizeof(get));
 169        if (ret || get.gpio != 0) {
 170                dev_err(gc->parent,
 171                        "Failed to get GPIO %u state (%d %x)\n", off, ret,
 172                        get.gpio);
 173                return ret ? ret : -EIO;
 174        }
 175        return !!get.state;
 176}
 177
 178static void rpi_exp_gpio_set(struct gpio_chip *gc, unsigned int off, int val)
 179{
 180        struct rpi_exp_gpio *gpio;
 181        struct gpio_get_set_state set;
 182        int ret;
 183
 184        gpio = gpiochip_get_data(gc);
 185
 186        set.gpio = off + RPI_EXP_GPIO_BASE;     /* GPIO to update */
 187        set.state = val;        /* Output state */
 188
 189        ret = rpi_firmware_property(gpio->fw, RPI_FIRMWARE_SET_GPIO_STATE,
 190                                         &set, sizeof(set));
 191        if (ret || set.gpio != 0)
 192                dev_err(gc->parent,
 193                        "Failed to set GPIO %u state (%d %x)\n", off, ret,
 194                        set.gpio);
 195}
 196
 197static int rpi_exp_gpio_probe(struct platform_device *pdev)
 198{
 199        struct device *dev = &pdev->dev;
 200        struct device_node *np = dev->of_node;
 201        struct device_node *fw_node;
 202        struct rpi_firmware *fw;
 203        struct rpi_exp_gpio *rpi_gpio;
 204
 205        fw_node = of_get_parent(np);
 206        if (!fw_node) {
 207                dev_err(dev, "Missing firmware node\n");
 208                return -ENOENT;
 209        }
 210
 211        fw = devm_rpi_firmware_get(&pdev->dev, fw_node);
 212        of_node_put(fw_node);
 213        if (!fw)
 214                return -EPROBE_DEFER;
 215
 216        rpi_gpio = devm_kzalloc(dev, sizeof(*rpi_gpio), GFP_KERNEL);
 217        if (!rpi_gpio)
 218                return -ENOMEM;
 219
 220        rpi_gpio->fw = fw;
 221        rpi_gpio->gc.parent = dev;
 222        rpi_gpio->gc.label = MODULE_NAME;
 223        rpi_gpio->gc.owner = THIS_MODULE;
 224        rpi_gpio->gc.of_node = np;
 225        rpi_gpio->gc.base = -1;
 226        rpi_gpio->gc.ngpio = NUM_GPIO;
 227
 228        rpi_gpio->gc.direction_input = rpi_exp_gpio_dir_in;
 229        rpi_gpio->gc.direction_output = rpi_exp_gpio_dir_out;
 230        rpi_gpio->gc.get_direction = rpi_exp_gpio_get_direction;
 231        rpi_gpio->gc.get = rpi_exp_gpio_get;
 232        rpi_gpio->gc.set = rpi_exp_gpio_set;
 233        rpi_gpio->gc.can_sleep = true;
 234
 235        return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
 236}
 237
 238static const struct of_device_id rpi_exp_gpio_ids[] = {
 239        { .compatible = "raspberrypi,firmware-gpio" },
 240        { }
 241};
 242MODULE_DEVICE_TABLE(of, rpi_exp_gpio_ids);
 243
 244static struct platform_driver rpi_exp_gpio_driver = {
 245        .driver = {
 246                .name           = MODULE_NAME,
 247                .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
 248        },
 249        .probe  = rpi_exp_gpio_probe,
 250};
 251module_platform_driver(rpi_exp_gpio_driver);
 252
 253MODULE_LICENSE("GPL");
 254MODULE_AUTHOR("Dave Stevenson <dave.stevenson@raspberrypi.org>");
 255MODULE_DESCRIPTION("Raspberry Pi 3 expander GPIO driver");
 256MODULE_ALIAS("platform:rpi-exp-gpio");
 257