1 /* 2 * PCF8575 I2C GPIO EXPANDER DRIVER 3 * 4 * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/ 5 * 6 * Vignesh R <vigneshr@ti.com> 7 * 8 * SPDX-License-Identifier: GPL-2.0 9 * 10 * 11 * Driver for TI PCF-8575 16-bit I2C gpio expander. Based on 12 * gpio-pcf857x Linux Kernel(v4.7) driver. 13 * 14 * Copyright (C) 2007 David Brownell 15 * 16 */ 17 18 /* 19 * NOTE: The driver and devicetree bindings are borrowed from Linux 20 * Kernel, but driver does not support all PCF857x devices. It currently 21 * supports PCF8575 16-bit expander by TI and NXP. 22 * 23 * TODO(vigneshr@ti.com): 24 * Support 8 bit PCF857x compatible expanders. 25 */ 26 27 #include <common.h> 28 #include <dm.h> 29 #include <i2c.h> 30 #include <asm-generic/gpio.h> 31 32 DECLARE_GLOBAL_DATA_PTR; 33 34 struct pcf8575_chip { 35 int gpio_count; /* No. GPIOs supported by the chip */ 36 37 /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. 38 * We can't actually know whether a pin is configured (a) as output 39 * and driving the signal low, or (b) as input and reporting a low 40 * value ... without knowing the last value written since the chip 41 * came out of reset (if any). We can't read the latched output. 42 * In short, the only reliable solution for setting up pin direction 43 * is to do it explicitly. 44 * 45 * Using "out" avoids that trouble. When left initialized to zero, 46 * our software copy of the "latch" then matches the chip's all-ones 47 * reset state. Otherwise it flags pins to be driven low. 48 */ 49 unsigned int out; /* software latch */ 50 const char *bank_name; /* Name of the expander bank */ 51 }; 52 53 /* Read/Write to 16-bit I/O expander */ 54 55 static int pcf8575_i2c_write_le16(struct udevice *dev, unsigned int word) 56 { 57 struct dm_i2c_chip *chip = dev_get_parent_platdata(dev); 58 u8 buf[2] = { word & 0xff, word >> 8, }; 59 int ret; 60 61 ret = dm_i2c_write(dev, 0, buf, 2); 62 if (ret) 63 printf("%s i2c write failed to addr %x\n", __func__, 64 chip->chip_addr); 65 66 return ret; 67 } 68 69 static int pcf8575_i2c_read_le16(struct udevice *dev) 70 { 71 struct dm_i2c_chip *chip = dev_get_parent_platdata(dev); 72 u8 buf[2]; 73 int ret; 74 75 ret = dm_i2c_read(dev, 0, buf, 2); 76 if (ret) { 77 printf("%s i2c read failed from addr %x\n", __func__, 78 chip->chip_addr); 79 return ret; 80 } 81 82 return (buf[1] << 8) | buf[0]; 83 } 84 85 static int pcf8575_direction_input(struct udevice *dev, unsigned offset) 86 { 87 struct pcf8575_chip *plat = dev_get_platdata(dev); 88 int status; 89 90 plat->out |= BIT(offset); 91 status = pcf8575_i2c_write_le16(dev, plat->out); 92 93 return status; 94 } 95 96 static int pcf8575_direction_output(struct udevice *dev, 97 unsigned int offset, int value) 98 { 99 struct pcf8575_chip *plat = dev_get_platdata(dev); 100 int ret; 101 102 if (value) 103 plat->out |= BIT(offset); 104 else 105 plat->out &= ~BIT(offset); 106 107 ret = pcf8575_i2c_write_le16(dev, plat->out); 108 109 return ret; 110 } 111 112 static int pcf8575_get_value(struct udevice *dev, unsigned int offset) 113 { 114 int value; 115 116 value = pcf8575_i2c_read_le16(dev); 117 118 return (value < 0) ? value : ((value & BIT(offset)) >> offset); 119 } 120 121 static int pcf8575_set_value(struct udevice *dev, unsigned int offset, 122 int value) 123 { 124 return pcf8575_direction_output(dev, offset, value); 125 } 126 127 static int pcf8575_ofdata_platdata(struct udevice *dev) 128 { 129 struct pcf8575_chip *plat = dev_get_platdata(dev); 130 struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev); 131 132 int n_latch; 133 134 uc_priv->gpio_count = fdtdec_get_int(gd->fdt_blob, dev->of_offset, 135 "gpio-count", 16); 136 uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev->of_offset, 137 "gpio-bank-name", NULL); 138 if (!uc_priv->bank_name) 139 uc_priv->bank_name = fdt_get_name(gd->fdt_blob, 140 dev->of_offset, NULL); 141 142 n_latch = fdtdec_get_uint(gd->fdt_blob, dev->of_offset, 143 "lines-initial-states", 0); 144 plat->out = ~n_latch; 145 146 return 0; 147 } 148 149 static int pcf8575_gpio_probe(struct udevice *dev) 150 { 151 struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev); 152 153 debug("%s GPIO controller with %d gpios probed\n", 154 uc_priv->bank_name, uc_priv->gpio_count); 155 156 return 0; 157 } 158 159 static const struct dm_gpio_ops pcf8575_gpio_ops = { 160 .direction_input = pcf8575_direction_input, 161 .direction_output = pcf8575_direction_output, 162 .get_value = pcf8575_get_value, 163 .set_value = pcf8575_set_value, 164 }; 165 166 static const struct udevice_id pcf8575_gpio_ids[] = { 167 { .compatible = "nxp,pcf8575" }, 168 { .compatible = "ti,pcf8575" }, 169 { } 170 }; 171 172 U_BOOT_DRIVER(gpio_pcf8575) = { 173 .name = "gpio_pcf8575", 174 .id = UCLASS_GPIO, 175 .ops = &pcf8575_gpio_ops, 176 .of_match = pcf8575_gpio_ids, 177 .ofdata_to_platdata = pcf8575_ofdata_platdata, 178 .probe = pcf8575_gpio_probe, 179 .platdata_auto_alloc_size = sizeof(struct pcf8575_chip), 180 }; 181