1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2006 Juergen Beisert, Pengutronix 4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix 5 * Copyright (C) 2009 Wolfram Sang, Pengutronix 6 * 7 * The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are 8 * 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more 9 * details 10 * Note: 11 * - DIN must be stable at the rising edge of clock. 12 * - when writing: 13 * - always clock in 16 clocks at once 14 * - at DIN: D15 first, D0 last 15 * - D0..D7 = databyte, D8..D14 = commandbyte 16 * - D15 = low -> write command 17 * - when reading 18 * - always clock in 16 clocks at once 19 * - at DIN: D15 first, D0 last 20 * - D0..D7 = dummy, D8..D14 = register address 21 * - D15 = high -> read command 22 * - raise CS and assert it again 23 * - always clock in 16 clocks at once 24 * - at DOUT: D15 first, D0 last 25 * - D0..D7 contains the data from the first cycle 26 * 27 * The driver exports a standard gpiochip interface 28 */ 29 30 #include <linux/module.h> 31 #include <linux/init.h> 32 #include <linux/platform_device.h> 33 #include <linux/mutex.h> 34 #include <linux/spi/max7301.h> 35 #include <linux/gpio/driver.h> 36 #include <linux/slab.h> 37 38 /* 39 * Pin configurations, see MAX7301 datasheet page 6 40 */ 41 #define PIN_CONFIG_MASK 0x03 42 #define PIN_CONFIG_IN_PULLUP 0x03 43 #define PIN_CONFIG_IN_WO_PULLUP 0x02 44 #define PIN_CONFIG_OUT 0x01 45 46 #define PIN_NUMBER 28 47 48 static int max7301_direction_input(struct gpio_chip *chip, unsigned offset) 49 { 50 struct max7301 *ts = container_of(chip, struct max7301, chip); 51 u8 *config; 52 u8 offset_bits, pin_config; 53 int ret; 54 55 /* First 4 pins are unused in the controller */ 56 offset += 4; 57 offset_bits = (offset & 3) << 1; 58 59 config = &ts->port_config[offset >> 2]; 60 61 if (ts->input_pullup_active & BIT(offset)) 62 pin_config = PIN_CONFIG_IN_PULLUP; 63 else 64 pin_config = PIN_CONFIG_IN_WO_PULLUP; 65 66 mutex_lock(&ts->lock); 67 68 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) 69 | (pin_config << offset_bits); 70 71 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); 72 73 mutex_unlock(&ts->lock); 74 75 return ret; 76 } 77 78 static int __max7301_set(struct max7301 *ts, unsigned offset, int value) 79 { 80 if (value) { 81 ts->out_level |= 1 << offset; 82 return ts->write(ts->dev, 0x20 + offset, 0x01); 83 } else { 84 ts->out_level &= ~(1 << offset); 85 return ts->write(ts->dev, 0x20 + offset, 0x00); 86 } 87 } 88 89 static int max7301_direction_output(struct gpio_chip *chip, unsigned offset, 90 int value) 91 { 92 struct max7301 *ts = container_of(chip, struct max7301, chip); 93 u8 *config; 94 u8 offset_bits; 95 int ret; 96 97 /* First 4 pins are unused in the controller */ 98 offset += 4; 99 offset_bits = (offset & 3) << 1; 100 101 config = &ts->port_config[offset >> 2]; 102 103 mutex_lock(&ts->lock); 104 105 *config = (*config & ~(PIN_CONFIG_MASK << offset_bits)) 106 | (PIN_CONFIG_OUT << offset_bits); 107 108 ret = __max7301_set(ts, offset, value); 109 110 if (!ret) 111 ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config); 112 113 mutex_unlock(&ts->lock); 114 115 return ret; 116 } 117 118 static int max7301_get(struct gpio_chip *chip, unsigned offset) 119 { 120 struct max7301 *ts = gpiochip_get_data(chip); 121 int config, level = -EINVAL; 122 123 /* First 4 pins are unused in the controller */ 124 offset += 4; 125 126 mutex_lock(&ts->lock); 127 128 config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1)) 129 & PIN_CONFIG_MASK; 130 131 switch (config) { 132 case PIN_CONFIG_OUT: 133 /* Output: return cached level */ 134 level = !!(ts->out_level & (1 << offset)); 135 break; 136 case PIN_CONFIG_IN_WO_PULLUP: 137 case PIN_CONFIG_IN_PULLUP: 138 /* Input: read out */ 139 level = ts->read(ts->dev, 0x20 + offset) & 0x01; 140 } 141 mutex_unlock(&ts->lock); 142 143 return level; 144 } 145 146 static void max7301_set(struct gpio_chip *chip, unsigned offset, int value) 147 { 148 struct max7301 *ts = gpiochip_get_data(chip); 149 150 /* First 4 pins are unused in the controller */ 151 offset += 4; 152 153 mutex_lock(&ts->lock); 154 155 __max7301_set(ts, offset, value); 156 157 mutex_unlock(&ts->lock); 158 } 159 160 int __max730x_probe(struct max7301 *ts) 161 { 162 struct device *dev = ts->dev; 163 struct max7301_platform_data *pdata; 164 int i, ret; 165 166 pdata = dev_get_platdata(dev); 167 168 mutex_init(&ts->lock); 169 dev_set_drvdata(dev, ts); 170 171 /* Power up the chip and disable IRQ output */ 172 ts->write(dev, 0x04, 0x01); 173 174 if (pdata) { 175 ts->input_pullup_active = pdata->input_pullup_active; 176 ts->chip.base = pdata->base; 177 } else { 178 ts->chip.base = -1; 179 } 180 ts->chip.label = dev->driver->name; 181 182 ts->chip.direction_input = max7301_direction_input; 183 ts->chip.get = max7301_get; 184 ts->chip.direction_output = max7301_direction_output; 185 ts->chip.set = max7301_set; 186 187 ts->chip.ngpio = PIN_NUMBER; 188 ts->chip.can_sleep = true; 189 ts->chip.parent = dev; 190 ts->chip.owner = THIS_MODULE; 191 192 /* 193 * initialize pullups according to platform data and cache the 194 * register values for later use. 195 */ 196 for (i = 1; i < 8; i++) { 197 int j; 198 /* 199 * initialize port_config with "0xAA", which means 200 * input with internal pullup disabled. This is needed 201 * to avoid writing zeros (in the inner for loop), 202 * which is not allowed according to the datasheet. 203 */ 204 ts->port_config[i] = 0xAA; 205 for (j = 0; j < 4; j++) { 206 int offset = (i - 1) * 4 + j; 207 ret = max7301_direction_input(&ts->chip, offset); 208 if (ret) 209 goto exit_destroy; 210 } 211 } 212 213 ret = gpiochip_add_data(&ts->chip, ts); 214 if (!ret) 215 return ret; 216 217 exit_destroy: 218 mutex_destroy(&ts->lock); 219 return ret; 220 } 221 EXPORT_SYMBOL_GPL(__max730x_probe); 222 223 void __max730x_remove(struct device *dev) 224 { 225 struct max7301 *ts = dev_get_drvdata(dev); 226 227 /* Power down the chip and disable IRQ output */ 228 ts->write(dev, 0x04, 0x00); 229 gpiochip_remove(&ts->chip); 230 mutex_destroy(&ts->lock); 231 } 232 EXPORT_SYMBOL_GPL(__max730x_remove); 233 234 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); 235 MODULE_LICENSE("GPL v2"); 236 MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts"); 237