1 // SPDX-License-Identifier: GPL-2.0
3 * PCF8575 I2C GPIO EXPANDER DRIVER
5 * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
7 * Vignesh R <vigneshr@ti.com>
10 * Driver for TI PCF-8575 16-bit I2C gpio expander. Based on
11 * gpio-pcf857x Linux Kernel(v4.7) driver.
13 * Copyright (C) 2007 David Brownell
18 * NOTE: The driver and devicetree bindings are borrowed from Linux
19 * Kernel, but driver does not support all PCF857x devices. It currently
20 * supports PCF8575 16-bit expander by TI and NXP.
22 * TODO(vigneshr@ti.com):
23 * Support 8 bit PCF857x compatible expanders.
30 #include <asm-generic/gpio.h>
31 #include <linux/bitops.h>
33 DECLARE_GLOBAL_DATA_PTR;
36 int gpio_count; /* No. GPIOs supported by the chip */
38 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
39 * We can't actually know whether a pin is configured (a) as output
40 * and driving the signal low, or (b) as input and reporting a low
41 * value ... without knowing the last value written since the chip
42 * came out of reset (if any). We can't read the latched output.
43 * In short, the only reliable solution for setting up pin direction
44 * is to do it explicitly.
46 * Using "out" avoids that trouble. When left initialized to zero,
47 * our software copy of the "latch" then matches the chip's all-ones
48 * reset state. Otherwise it flags pins to be driven low.
50 unsigned int out; /* software latch */
51 const char *bank_name; /* Name of the expander bank */
54 /* Read/Write to 16-bit I/O expander */
56 static int pcf8575_i2c_write_le16(struct udevice *dev, unsigned int word)
58 struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
59 u8 buf[2] = { word & 0xff, word >> 8, };
62 ret = dm_i2c_write(dev, 0, buf, 2);
64 printf("%s i2c write failed to addr %x\n", __func__,
70 static int pcf8575_i2c_read_le16(struct udevice *dev)
72 struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
76 ret = dm_i2c_read(dev, 0, buf, 2);
78 printf("%s i2c read failed from addr %x\n", __func__,
83 return (buf[1] << 8) | buf[0];
86 static int pcf8575_direction_input(struct udevice *dev, unsigned offset)
88 struct pcf8575_chip *plat = dev_get_platdata(dev);
91 plat->out |= BIT(offset);
92 status = pcf8575_i2c_write_le16(dev, plat->out);
97 static int pcf8575_direction_output(struct udevice *dev,
98 unsigned int offset, int value)
100 struct pcf8575_chip *plat = dev_get_platdata(dev);
104 plat->out |= BIT(offset);
106 plat->out &= ~BIT(offset);
108 ret = pcf8575_i2c_write_le16(dev, plat->out);
113 static int pcf8575_get_value(struct udevice *dev, unsigned int offset)
117 value = pcf8575_i2c_read_le16(dev);
119 return (value < 0) ? value : ((value & BIT(offset)) >> offset);
122 static int pcf8575_set_value(struct udevice *dev, unsigned int offset,
125 return pcf8575_direction_output(dev, offset, value);
128 static int pcf8575_ofdata_platdata(struct udevice *dev)
130 struct pcf8575_chip *plat = dev_get_platdata(dev);
131 struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
135 uc_priv->gpio_count = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
137 uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev_of_offset(dev),
138 "gpio-bank-name", NULL);
139 if (!uc_priv->bank_name)
140 uc_priv->bank_name = fdt_get_name(gd->fdt_blob,
141 dev_of_offset(dev), NULL);
143 n_latch = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev),
144 "lines-initial-states", 0);
145 plat->out = ~n_latch;
150 static int pcf8575_gpio_probe(struct udevice *dev)
152 struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
154 debug("%s GPIO controller with %d gpios probed\n",
155 uc_priv->bank_name, uc_priv->gpio_count);
160 static const struct dm_gpio_ops pcf8575_gpio_ops = {
161 .direction_input = pcf8575_direction_input,
162 .direction_output = pcf8575_direction_output,
163 .get_value = pcf8575_get_value,
164 .set_value = pcf8575_set_value,
167 static const struct udevice_id pcf8575_gpio_ids[] = {
168 { .compatible = "nxp,pcf8575" },
169 { .compatible = "ti,pcf8575" },
173 U_BOOT_DRIVER(gpio_pcf8575) = {
174 .name = "gpio_pcf8575",
176 .ops = &pcf8575_gpio_ops,
177 .of_match = pcf8575_gpio_ids,
178 .ofdata_to_platdata = pcf8575_ofdata_platdata,
179 .probe = pcf8575_gpio_probe,
180 .platdata_auto = sizeof(struct pcf8575_chip),