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");