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.
29 #include <asm-generic/gpio.h>
31 DECLARE_GLOBAL_DATA_PTR;
34 int gpio_count; /* No. GPIOs supported by the chip */
36 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
37 * We can't actually know whether a pin is configured (a) as output
38 * and driving the signal low, or (b) as input and reporting a low
39 * value ... without knowing the last value written since the chip
40 * came out of reset (if any). We can't read the latched output.
41 * In short, the only reliable solution for setting up pin direction
42 * is to do it explicitly.
44 * Using "out" avoids that trouble. When left initialized to zero,
45 * our software copy of the "latch" then matches the chip's all-ones
46 * reset state. Otherwise it flags pins to be driven low.
48 unsigned int out; /* software latch */
49 const char *bank_name; /* Name of the expander bank */
52 /* Read/Write to 16-bit I/O expander */
54 static int pcf8575_i2c_write_le16(struct udevice *dev, unsigned int word)
56 struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
57 u8 buf[2] = { word & 0xff, word >> 8, };
60 ret = dm_i2c_write(dev, 0, buf, 2);
62 printf("%s i2c write failed to addr %x\n", __func__,
68 static int pcf8575_i2c_read_le16(struct udevice *dev)
70 struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
74 ret = dm_i2c_read(dev, 0, buf, 2);
76 printf("%s i2c read failed from addr %x\n", __func__,
81 return (buf[1] << 8) | buf[0];
84 static int pcf8575_direction_input(struct udevice *dev, unsigned offset)
86 struct pcf8575_chip *plat = dev_get_platdata(dev);
89 plat->out |= BIT(offset);
90 status = pcf8575_i2c_write_le16(dev, plat->out);
95 static int pcf8575_direction_output(struct udevice *dev,
96 unsigned int offset, int value)
98 struct pcf8575_chip *plat = dev_get_platdata(dev);
102 plat->out |= BIT(offset);
104 plat->out &= ~BIT(offset);
106 ret = pcf8575_i2c_write_le16(dev, plat->out);
111 static int pcf8575_get_value(struct udevice *dev, unsigned int offset)
115 value = pcf8575_i2c_read_le16(dev);
117 return (value < 0) ? value : ((value & BIT(offset)) >> offset);
120 static int pcf8575_set_value(struct udevice *dev, unsigned int offset,
123 return pcf8575_direction_output(dev, offset, value);
126 static int pcf8575_ofdata_platdata(struct udevice *dev)
128 struct pcf8575_chip *plat = dev_get_platdata(dev);
129 struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
133 uc_priv->gpio_count = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
135 uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev_of_offset(dev),
136 "gpio-bank-name", NULL);
137 if (!uc_priv->bank_name)
138 uc_priv->bank_name = fdt_get_name(gd->fdt_blob,
139 dev_of_offset(dev), NULL);
141 n_latch = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev),
142 "lines-initial-states", 0);
143 plat->out = ~n_latch;
148 static int pcf8575_gpio_probe(struct udevice *dev)
150 struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
152 debug("%s GPIO controller with %d gpios probed\n",
153 uc_priv->bank_name, uc_priv->gpio_count);
158 static const struct dm_gpio_ops pcf8575_gpio_ops = {
159 .direction_input = pcf8575_direction_input,
160 .direction_output = pcf8575_direction_output,
161 .get_value = pcf8575_get_value,
162 .set_value = pcf8575_set_value,
165 static const struct udevice_id pcf8575_gpio_ids[] = {
166 { .compatible = "nxp,pcf8575" },
167 { .compatible = "ti,pcf8575" },
171 U_BOOT_DRIVER(gpio_pcf8575) = {
172 .name = "gpio_pcf8575",
174 .ops = &pcf8575_gpio_ops,
175 .of_match = pcf8575_gpio_ids,
176 .ofdata_to_platdata = pcf8575_ofdata_platdata,
177 .probe = pcf8575_gpio_probe,
178 .platdata_auto_alloc_size = sizeof(struct pcf8575_chip),