1 /** 2 * Copyright (C) 2006 Juergen Beisert, Pengutronix 3 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix 4 * Copyright (C) 2009 Wolfram Sang, Pengutronix 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are 11 * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more 12 * details 13 * Note: 14 * - DIN must be stable at the rising edge of clock. 15 * - when writing: 16 * - always clock in 16 clocks at once 17 * - at DIN: D15 first, D0 last 18 * - D0..D7 = databyte, D8..D14 = commandbyte 19 * - D15 = low -> write command 20 * - when reading 21 * - always clock in 16 clocks at once 22 * - at DIN: D15 first, D0 last 23 * - D0..D7 = dummy, D8..D14 = register address 24 * - D15 = high -> read command 25 * - raise CS and assert it again 26 * - always clock in 16 clocks at once 27 * - at DOUT: D15 first, D0 last 28 * - D0..D7 contains the data from the first cycle 29 * 30 * The driver exports a standard gpiochip interface 31 */ 32 33 #include <linux/module.h> 34 #include <linux/init.h> 35 #include <linux/platform_device.h> 36 #include <linux/mutex.h> 37 #include <linux/spi/max7301.h> 38 #include <linux/gpio.h> 39 #include <linux/slab.h> 40 41 /* 42 * Pin configurations, see MAX7301 datasheet page 6 43 */ 44 #define PIN_CONFIG_MASK 0x03 45 #define PIN_CONFIG_IN_PULLUP 0x03 46 #define PIN_CONFIG_IN_WO_PULLUP 0x02 47 #define PIN_CONFIG_OUT 0x01 48 49 #define PIN_NUMBER 28 50 51 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset) 52 { 53 struct max7301 *ts = container_of(chip, struct max7301, chip); 54 u8 *config; 55 u8 offset_bits, pin_config; 56 int ret; 57 58 /* First 4 pins are unused in the controller */ 59 offset += 4; 60 offset_bits = (offset & 3) << 1; 61 62 config = &ts->port_config[offset >> 2]; 63 64 if (ts->input_pullup_active & BIT(offset)) 65 pin_config = PIN_CONFIG_IN_PULLUP; 66 else 67 pin_config = PIN_CONFIG_IN_WO_PULLUP; 68 69 mutex_lock(&ts->lock); 70 71 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) 72 | (pin_config << offset_bits); 73 74 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); 75 76 mutex_unlock(&ts->lock); 77 78 return ret; 79 } 80 81 static int __max7301_set(struct max7301 *ts, unsigned offset, int value) 82 { 83 if (value) { 84 ts->out_level |= 1 << offset; 85 return ts->write(ts->dev, 0x20 + offset, 0x01); 86 } else { 87 ts->out_level &= ~(1 << offset); 88 return ts->write(ts->dev, 0x20 + offset, 0x00); 89 } 90 } 91 92 static int max7301_direction_output(struct gpio_chip *chip, unsigned offset, 93 int value) 94 { 95 struct max7301 *ts = container_of(chip, struct max7301, chip); 96 u8 *config; 97 u8 offset_bits; 98 int ret; 99 100 /* First 4 pins are unused in the controller */ 101 offset += 4; 102 offset_bits = (offset & 3) << 1; 103 104 config = &ts->port_config[offset >> 2]; 105 106 mutex_lock(&ts->lock); 107 108 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) 109 | (PIN_CONFIG_OUT << offset_bits); 110 111 ret = __max7301_set(ts, offset, value); 112 113 if (!ret) 114 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); 115 116 mutex_unlock(&ts->lock); 117 118 return ret; 119 } 120 121 static int max7301_get(struct gpio_chip *chip, unsigned offset) 122 { 123 struct max7301 *ts = container_of(chip, struct max7301, chip); 124 int config, level = -EINVAL; 125 126 /* First 4 pins are unused in the controller */ 127 offset += 4; 128 129 mutex_lock(&ts->lock); 130 131 config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1)) 132 & PIN_CONFIG_MASK; 133 134 switch (config) { 135 case PIN_CONFIG_OUT: 136 /* Output: return cached level */ 137 level = !!(ts->out_level & (1 << offset)); 138 break; 139 case PIN_CONFIG_IN_WO_PULLUP: 140 case PIN_CONFIG_IN_PULLUP: 141 /* Input: read out */ 142 level = ts->read(ts->dev, 0x20 + offset) & 0x01; 143 } 144 mutex_unlock(&ts->lock); 145 146 return level; 147 } 148 149 static void max7301_set(struct gpio_chip *chip, unsigned offset, int value) 150 { 151 struct max7301 *ts = container_of(chip, struct max7301, chip); 152 153 /* First 4 pins are unused in the controller */ 154 offset += 4; 155 156 mutex_lock(&ts->lock); 157 158 __max7301_set(ts, offset, value); 159 160 mutex_unlock(&ts->lock); 161 } 162 163 int __max730x_probe(struct max7301 *ts) 164 { 165 struct device *dev = ts->dev; 166 struct max7301_platform_data *pdata; 167 int i, ret; 168 169 pdata = dev_get_platdata(dev); 170 171 mutex_init(&ts->lock); 172 dev_set_drvdata(dev, ts); 173 174 /* Power up the chip and disable IRQ output */ 175 ts->write(dev, 0x04, 0x01); 176 177 if (pdata) { 178 ts->input_pullup_active = pdata->input_pullup_active; 179 ts->chip.base = pdata->base; 180 } else { 181 ts->chip.base = -1; 182 } 183 ts->chip.label = dev->driver->name; 184 185 ts->chip.direction_input = max7301_direction_input; 186 ts->chip.get = max7301_get; 187 ts->chip.direction_output = max7301_direction_output; 188 ts->chip.set = max7301_set; 189 190 ts->chip.ngpio = PIN_NUMBER; 191 ts->chip.can_sleep = true; 192 ts->chip.dev = dev; 193 ts->chip.owner = THIS_MODULE; 194 195 /* 196 * initialize pullups according to platform data and cache the 197 * register values for later use. 198 */ 199 for (i = 1; i < 8; i++) { 200 int j; 201 /* 202 * initialize port_config with "0xAA", which means 203 * input with internal pullup disabled. This is needed 204 * to avoid writing zeros (in the inner for loop), 205 * which is not allowed according to the datasheet. 206 */ 207 ts->port_config[i] = 0xAA; 208 for (j = 0; j < 4; j++) { 209 int offset = (i - 1) * 4 + j; 210 ret = max7301_direction_input(&ts->chip, offset); 211 if (ret) 212 goto exit_destroy; 213 } 214 } 215 216 ret = gpiochip_add(&ts->chip); 217 if (ret) 218 goto exit_destroy; 219 220 return ret; 221 222 exit_destroy: 223 mutex_destroy(&ts->lock); 224 return ret; 225 } 226 EXPORT_SYMBOL_GPL(__max730x_probe); 227 228 int __max730x_remove(struct device *dev) 229 { 230 struct max7301 *ts = dev_get_drvdata(dev); 231 int ret; 232 233 if (ts == NULL) 234 return -ENODEV; 235 236 /* Power down the chip and disable IRQ output */ 237 ts->write(dev, 0x04, 0x00); 238 239 ret = gpiochip_remove(&ts->chip); 240 if (!ret) 241 mutex_destroy(&ts->lock); 242 else 243 dev_err(dev, "Failed to remove GPIO controller: %d\n", ret); 244 245 return ret; 246 } 247 EXPORT_SYMBOL_GPL(__max730x_remove); 248 249 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); 250 MODULE_LICENSE("GPL v2"); 251 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts"); 252