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