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
  20 struct 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
  28 static 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
  40 static 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
  57 static 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 */
  80 static 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 */
  86 static 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  */
 114 static 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
 130 static 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
 173 static struct platform_driver gpo_bd71815_driver = {
 174         .driver = {
 175                 .name   = "bd71815-gpo",
 176         },
 177         .probe          = gpo_bd71815_probe,
 178 };
 179 module_platform_driver(gpo_bd71815_driver);
 180
 181 MODULE_ALIAS("platform:bd71815-gpo");
 182 MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
 183 MODULE_AUTHOR("Peter Yang <yanglsh@embest-tech.com>");
 184 MODULE_DESCRIPTION("GPO interface for BD71815");
 185 MODULE_LICENSE("GPL");