LXR linux/drivers/gpio/gpio-bd71815.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Support to GPOs on ROHM BD71815
   4 * Copyright 2021 ROHM Semiconductors.
   5 * Author: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
   6 *
   7 * Copyright 2014 Embest Technology Co. Ltd. Inc.
   8 * Author: yanglsh@embest-tech.com
   9 */
  10
  11#include <linux/gpio/driver.h>
  12#include <linux/init.h>
  13#include <linux/irq.h>
  14#include <linux/module.h>
  15#include <linux/of.h>
  16#include <linux/platform_device.h>
  17/* For the BD71815 register definitions */
  18#include <linux/mfd/rohm-bd71815.h>
  19
  20struct bd71815_gpio {
  21        /* chip.parent points the MFD which provides DT node and regmap */
  22        struct gpio_chip chip;
  23        /* dev points to the platform device for devm and prints */
  24        struct device *dev;
  25        struct regmap *regmap;
  26};
  27
  28static int bd71815gpo_get(struct gpio_chip *chip, unsigned int offset)
  29{
  30        struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
  31        int ret, val;
  32
  33        ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val);
  34        if (ret)
  35                return ret;
  36
  37        return (val >> offset) & 1;
  38}
  39
  40static void bd71815gpo_set(struct gpio_chip *chip, unsigned int offset,
  41                           int value)
  42{
  43        struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
  44        int ret, bit;
  45
  46        bit = BIT(offset);
  47
  48        if (value)
  49                ret = regmap_set_bits(bd71815->regmap, BD71815_REG_GPO, bit);
  50        else
  51                ret = regmap_clear_bits(bd71815->regmap, BD71815_REG_GPO, bit);
  52
  53        if (ret)
  54                dev_warn(bd71815->dev, "failed to toggle GPO\n");
  55}
  56
  57static int bd71815_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
  58                                   unsigned long config)
  59{
  60        struct bd71815_gpio *bdgpio = gpiochip_get_data(chip);
  61
  62        switch (pinconf_to_config_param(config)) {
  63        case PIN_CONFIG_DRIVE_OPEN_DRAIN:
  64                return regmap_update_bits(bdgpio->regmap,
  65                                          BD71815_REG_GPO,
  66                                          BD71815_GPIO_DRIVE_MASK << offset,
  67                                          BD71815_GPIO_OPEN_DRAIN << offset);
  68        case PIN_CONFIG_DRIVE_PUSH_PULL:
  69                return regmap_update_bits(bdgpio->regmap,
  70                                          BD71815_REG_GPO,
  71                                          BD71815_GPIO_DRIVE_MASK << offset,
  72                                          BD71815_GPIO_CMOS << offset);
  73        default:
  74                break;
  75        }
  76        return -ENOTSUPP;
  77}
  78
  79/* BD71815 GPIO is actually GPO */
  80static int bd71815gpo_direction_get(struct gpio_chip *gc, unsigned int offset)
  81{
  82        return GPIO_LINE_DIRECTION_OUT;
  83}
  84
  85/* Template for GPIO chip */
  86static const struct gpio_chip bd71815gpo_chip = {
  87        .label                  = "bd71815",
  88        .owner                  = THIS_MODULE,
  89        .get                    = bd71815gpo_get,
  90        .get_direction          = bd71815gpo_direction_get,
  91        .set                    = bd71815gpo_set,
  92        .set_config             = bd71815_gpio_set_config,
  93        .can_sleep              = true,
  94};
  95
  96#define BD71815_TWO_GPIOS       GENMASK(1, 0)
  97#define BD71815_ONE_GPIO        BIT(0)
  98
  99/*
 100 * Sigh. The BD71815 and BD71817 were originally designed to support two GPO
 101 * pins. At some point it was noticed the second GPO pin which is the E5 pin
 102 * located at the center of IC is hard to use on PCB (due to the location). It
 103 * was decided to not promote this second GPO and the pin is marked as GND in
 104 * the datasheet. The functionality is still there though! I guess driving a GPO
 105 * connected to the ground is a bad idea. Thus we do not support it by default.
 106 * OTOH - the original driver written by colleagues at Embest did support
 107 * controlling this second GPO. It is thus possible this is used in some of the
 108 * products.
 109 *
 110 * This driver does not by default support configuring this second GPO
 111 * but allows using it by providing the DT property
 112 * "rohm,enable-hidden-gpo".
 113 */
 114static int bd71815_init_valid_mask(struct gpio_chip *gc,
 115                                   unsigned long *valid_mask,
 116                                   unsigned int ngpios)
 117{
 118        if (ngpios != 2)
 119                return 0;
 120
 121        if (gc->parent && device_property_present(gc->parent,
 122                                                  "rohm,enable-hidden-gpo"))
 123                *valid_mask = BD71815_TWO_GPIOS;
 124        else
 125                *valid_mask = BD71815_ONE_GPIO;
 126
 127        return 0;
 128}
 129
 130static int gpo_bd71815_probe(struct platform_device *pdev)
 131{
 132        struct bd71815_gpio *g;
 133        struct device *parent, *dev;
 134
 135        /*
 136         * Bind devm lifetime to this platform device => use dev for devm.
 137         * also the prints should originate from this device.
 138         */
 139        dev = &pdev->dev;
 140        /* The device-tree and regmap come from MFD => use parent for that */
 141        parent = dev->parent;
 142
 143        g = devm_kzalloc(dev, sizeof(*g), GFP_KERNEL);
 144        if (!g)
 145                return -ENOMEM;
 146
 147        g->chip = bd71815gpo_chip;
 148
 149        /*
 150         * FIXME: As writing of this the sysfs interface for GPIO control does
 151         * not respect the valid_mask. Do not trust it but rather set the ngpios
 152         * to 1 if "rohm,enable-hidden-gpo" is not given.
 153         *
 154         * This check can be removed later if the sysfs export is fixed and
 155         * if the fix is backported.
 156         *
 157         * For now it is safest to just set the ngpios though.
 158         */
 159        if (device_property_present(parent, "rohm,enable-hidden-gpo"))
 160                g->chip.ngpio = 2;
 161        else
 162                g->chip.ngpio = 1;
 163
 164        g->chip.init_valid_mask = bd71815_init_valid_mask;
 165        g->chip.base = -1;
 166        g->chip.parent = parent;
 167        g->regmap = dev_get_regmap(parent, NULL);
 168        g->dev = dev;
 169
 170        return devm_gpiochip_add_data(dev, &g->chip, g);
 171}
 172
 173static struct platform_driver gpo_bd71815_driver = {
 174        .driver = {
 175                .name   = "bd71815-gpo",
 176        },
 177        .probe          = gpo_bd71815_probe,
 178};
 179module_platform_driver(gpo_bd71815_driver);
 180
 181MODULE_ALIAS("platform:bd71815-gpo");
 182MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
 183MODULE_AUTHOR("Peter Yang <yanglsh@embest-tech.com>");
 184MODULE_DESCRIPTION("GPO interface for BD71815");
 185MODULE_LICENSE("GPL");
 186