drivers/gpio/pcf8575_gpio.c

   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(dev),
 135                                              "gpio-count", 16);
 136         uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev_of_offset(dev),
 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(dev), NULL);
 141
 142         n_latch = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev),
 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 };