1/*
  2 * GPIO driver for EXAR XRA1403 16-bit GPIO expander
  3 *
  4 * Copyright (c) 2017, General Electric Company
  5 *
  6 * This program is free software; you can redistribute it and/or modify it
  7 * under the terms and conditions of the GNU General Public License,
  8 * version 2, as published by the Free Software Foundation.
  9 *
 10 * This program is distributed in the hope it will be useful, but WITHOUT
 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 13 * more details.
 14 *
 15 * You should have received a copy of the GNU General Public License
 16 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 17 */
 18
 19#include <linux/bitops.h>
 20#include <linux/gpio/driver.h>
 21#include <linux/kernel.h>
 22#include <linux/module.h>
 23#include <linux/mutex.h>
 24#include <linux/of_device.h>
 25#include <linux/of_gpio.h>
 26#include <linux/seq_file.h>
 27#include <linux/spi/spi.h>
 28#include <linux/regmap.h>
 29
 30/* XRA1403 registers */
 31#define XRA_GSR   0x00 /* GPIO State */
 32#define XRA_OCR   0x02 /* Output Control */
 33#define XRA_PIR   0x04 /* Input Polarity Inversion */
 34#define XRA_GCR   0x06 /* GPIO Configuration */
 35#define XRA_PUR   0x08 /* Input Internal Pull-up Resistor Enable/Disable */
 36#define XRA_IER   0x0A /* Input Interrupt Enable */
 37#define XRA_TSCR  0x0C /* Output Three-State Control */
 38#define XRA_ISR   0x0E /* Input Interrupt Status */
 39#define XRA_REIR  0x10 /* Input Rising Edge Interrupt Enable */
 40#define XRA_FEIR  0x12 /* Input Falling Edge Interrupt Enable */
 41#define XRA_IFR   0x14 /* Input Filter Enable/Disable */
 42
 43struct xra1403 {
 44	struct gpio_chip  chip;
 45	struct regmap     *regmap;
 46};
 47
 48static const struct regmap_config xra1403_regmap_cfg = {
 49		.reg_bits = 7,
 50		.pad_bits = 1,
 51		.val_bits = 8,
 52
 53		.max_register = XRA_IFR | 0x01,
 54};
 55
 56static unsigned int to_reg(unsigned int reg, unsigned int offset)
 57{
 58	return reg + (offset > 7);
 59}
 60
 61static int xra1403_direction_input(struct gpio_chip *chip, unsigned int offset)
 62{
 63	struct xra1403 *xra = gpiochip_get_data(chip);
 64
 65	return regmap_update_bits(xra->regmap, to_reg(XRA_GCR, offset),
 66			BIT(offset % 8), BIT(offset % 8));
 67}
 68
 69static int xra1403_direction_output(struct gpio_chip *chip, unsigned int offset,
 70				    int value)
 71{
 72	int ret;
 73	struct xra1403 *xra = gpiochip_get_data(chip);
 74
 75	ret = regmap_update_bits(xra->regmap, to_reg(XRA_GCR, offset),
 76			BIT(offset % 8), 0);
 77	if (ret)
 78		return ret;
 79
 80	ret = regmap_update_bits(xra->regmap, to_reg(XRA_OCR, offset),
 81			BIT(offset % 8), value ? BIT(offset % 8) : 0);
 82
 83	return ret;
 84}
 85
 86static int xra1403_get_direction(struct gpio_chip *chip, unsigned int offset)
 87{
 88	int ret;
 89	unsigned int val;
 90	struct xra1403 *xra = gpiochip_get_data(chip);
 91
 92	ret = regmap_read(xra->regmap, to_reg(XRA_GCR, offset), &val);
 93	if (ret)
 94		return ret;
 95
 96	return !!(val & BIT(offset % 8));
 97}
 98
 99static int xra1403_get(struct gpio_chip *chip, unsigned int offset)
100{
101	int ret;
102	unsigned int val;
103	struct xra1403 *xra = gpiochip_get_data(chip);
104
105	ret = regmap_read(xra->regmap, to_reg(XRA_GSR, offset), &val);
106	if (ret)
107		return ret;
108
109	return !!(val & BIT(offset % 8));
110}
111
112static void xra1403_set(struct gpio_chip *chip, unsigned int offset, int value)
113{
114	int ret;
115	struct xra1403 *xra = gpiochip_get_data(chip);
116
117	ret = regmap_update_bits(xra->regmap, to_reg(XRA_OCR, offset),
118			BIT(offset % 8), value ? BIT(offset % 8) : 0);
119	if (ret)
120		dev_err(chip->parent, "Failed to set pin: %d, ret: %d\n",
121				offset, ret);
122}
123
124#ifdef CONFIG_DEBUG_FS
125static void xra1403_dbg_show(struct seq_file *s, struct gpio_chip *chip)
126{
127	int reg;
128	struct xra1403 *xra = gpiochip_get_data(chip);
129	int *value;
130	int i;
131	unsigned int gcr;
132	unsigned int gsr;
133
134	value = kmalloc_array(xra1403_regmap_cfg.max_register, sizeof(*value),
135				GFP_KERNEL);
136	if (!value)
137		return;
138
139	seq_puts(s, "xra reg:");
140	for (reg = 0; reg <= xra1403_regmap_cfg.max_register; reg++)
141		seq_printf(s, " %2.2x", reg);
142	seq_puts(s, "\n  value:");
143	for (reg = 0; reg < xra1403_regmap_cfg.max_register; reg++) {
144		regmap_read(xra->regmap, reg, &value[reg]);
145		seq_printf(s, " %2.2x", value[reg]);
146	}
147	seq_puts(s, "\n");
148
149	gcr = value[XRA_GCR + 1] << 8 | value[XRA_GCR];
150	gsr = value[XRA_GSR + 1] << 8 | value[XRA_GSR];
151	for (i = 0; i < chip->ngpio; i++) {
152		const char *label = gpiochip_is_requested(chip, i);
153
154		if (!label)
155			continue;
156
157		seq_printf(s, " gpio-%-3d (%-12s) %s %s\n",
158			   chip->base + i, label,
159			   (gcr & BIT(i)) ? "in" : "out",
160			   (gsr & BIT(i)) ? "hi" : "lo");
161	}
162	kfree(value);
163}
164#else
165#define xra1403_dbg_show NULL
166#endif
167
168static int xra1403_probe(struct spi_device *spi)
169{
170	struct xra1403 *xra;
171	struct gpio_desc *reset_gpio;
172	int ret;
173
174	xra = devm_kzalloc(&spi->dev, sizeof(*xra), GFP_KERNEL);
175	if (!xra)
176		return -ENOMEM;
177
178	/* bring the chip out of reset if reset pin is provided*/
179	reset_gpio = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_LOW);
180	if (IS_ERR(reset_gpio))
181		dev_warn(&spi->dev, "Could not get reset-gpios\n");
182
183	xra->chip.direction_input = xra1403_direction_input;
184	xra->chip.direction_output = xra1403_direction_output;
185	xra->chip.get_direction = xra1403_get_direction;
186	xra->chip.get = xra1403_get;
187	xra->chip.set = xra1403_set;
188
189	xra->chip.dbg_show = xra1403_dbg_show;
190
191	xra->chip.ngpio = 16;
192	xra->chip.label = "xra1403";
193
194	xra->chip.base = -1;
195	xra->chip.can_sleep = true;
196	xra->chip.parent = &spi->dev;
197	xra->chip.owner = THIS_MODULE;
198
199	xra->regmap = devm_regmap_init_spi(spi, &xra1403_regmap_cfg);
200	if (IS_ERR(xra->regmap)) {
201		ret = PTR_ERR(xra->regmap);
202		dev_err(&spi->dev, "Failed to allocate regmap: %d\n", ret);
203		return ret;
204	}
205
206	ret = devm_gpiochip_add_data(&spi->dev, &xra->chip, xra);
207	if (ret < 0) {
208		dev_err(&spi->dev, "Unable to register gpiochip\n");
209		return ret;
210	}
211
212	spi_set_drvdata(spi, xra);
213
214	return 0;
215}
216
217static const struct spi_device_id xra1403_ids[] = {
218	{ "xra1403" },
219	{},
220};
221MODULE_DEVICE_TABLE(spi, xra1403_ids);
222
223static const struct of_device_id xra1403_spi_of_match[] = {
224	{ .compatible = "exar,xra1403" },
225	{},
226};
227MODULE_DEVICE_TABLE(of, xra1403_spi_of_match);
228
229static struct spi_driver xra1403_driver = {
230	.probe    = xra1403_probe,
231	.id_table = xra1403_ids,
232	.driver   = {
233		.name           = "xra1403",
234		.of_match_table = of_match_ptr(xra1403_spi_of_match),
235	},
236};
237
238module_spi_driver(xra1403_driver);
239
240MODULE_AUTHOR("Nandor Han <nandor.han@ge.com>");
241MODULE_AUTHOR("Semi Malinen <semi.malinen@ge.com>");
242MODULE_DESCRIPTION("GPIO expander driver for EXAR XRA1403");
243MODULE_LICENSE("GPL v2");