2 * (C) Copyright 2015, Samsung Electronics
3 * Przemyslaw Marczak <p.marczak@samsung.com>
5 * This file is based on: drivers/i2c/soft-i2c.c,
6 * with added driver-model support and code cleanup.
14 #define DEFAULT_UDELAY 5
19 DECLARE_GLOBAL_DATA_PTR;
29 * udelay - delay [us] between GPIO toggle operations,
30 * which is 1/4 of I2C speed clock period.
34 struct gpio_desc gpios[PIN_COUNT];
37 static int i2c_gpio_sda_get(struct gpio_desc *sda)
39 return dm_gpio_get_value(sda);
42 static void i2c_gpio_sda_set(struct gpio_desc *sda, int bit)
45 dm_gpio_set_dir_flags(sda, GPIOD_IS_IN);
47 dm_gpio_set_dir_flags(sda, GPIOD_IS_OUT);
50 static void i2c_gpio_scl_set(struct gpio_desc *scl, int bit)
52 ulong flags = GPIOD_IS_OUT;
55 flags |= GPIOD_IS_OUT_ACTIVE;
56 dm_gpio_set_dir_flags(scl, flags);
59 static void i2c_gpio_write_bit(struct gpio_desc *scl, struct gpio_desc *sda,
62 i2c_gpio_scl_set(scl, 0);
64 i2c_gpio_sda_set(sda, bit);
66 i2c_gpio_scl_set(scl, 1);
70 static int i2c_gpio_read_bit(struct gpio_desc *scl, struct gpio_desc *sda,
75 i2c_gpio_scl_set(scl, 1);
77 value = i2c_gpio_sda_get(sda);
79 i2c_gpio_scl_set(scl, 0);
85 /* START: High -> Low on SDA while SCL is High */
86 static void i2c_gpio_send_start(struct gpio_desc *scl, struct gpio_desc *sda,
90 i2c_gpio_sda_set(sda, 1);
92 i2c_gpio_scl_set(scl, 1);
94 i2c_gpio_sda_set(sda, 0);
98 /* STOP: Low -> High on SDA while SCL is High */
99 static void i2c_gpio_send_stop(struct gpio_desc *scl, struct gpio_desc *sda,
102 i2c_gpio_scl_set(scl, 0);
104 i2c_gpio_sda_set(sda, 0);
106 i2c_gpio_scl_set(scl, 1);
108 i2c_gpio_sda_set(sda, 1);
112 /* ack should be I2C_ACK or I2C_NOACK */
113 static void i2c_gpio_send_ack(struct gpio_desc *scl, struct gpio_desc *sda,
116 i2c_gpio_write_bit(scl, sda, delay, ack);
117 i2c_gpio_scl_set(scl, 0);
122 * Send a reset sequence consisting of 9 clocks with the data signal high
123 * to clock any confused device back into an idle state. Also send a
124 * <stop> at the end of the sequence for belts & suspenders.
126 static void i2c_gpio_send_reset(struct gpio_desc *scl, struct gpio_desc *sda,
131 for (j = 0; j < 9; j++)
132 i2c_gpio_write_bit(scl, sda, delay, 1);
134 i2c_gpio_send_stop(scl, sda, delay);
137 /* Set sda high with low clock, before reading slave data */
138 static void i2c_gpio_sda_high(struct gpio_desc *scl, struct gpio_desc *sda,
141 i2c_gpio_scl_set(scl, 0);
143 i2c_gpio_sda_set(sda, 1);
147 /* Send 8 bits and look for an acknowledgement */
148 static int i2c_gpio_write_byte(struct gpio_desc *scl, struct gpio_desc *sda,
149 int delay, uchar data)
154 for (j = 0; j < 8; j++) {
155 i2c_gpio_write_bit(scl, sda, delay, data & 0x80);
161 /* Look for an <ACK>(negative logic) and return it */
162 i2c_gpio_sda_high(scl, sda, delay);
163 nack = i2c_gpio_read_bit(scl, sda, delay);
165 return nack; /* not a nack is an ack */
169 * if ack == I2C_ACK, ACK the byte so can continue reading, else
170 * send I2C_NOACK to end the read.
172 static uchar i2c_gpio_read_byte(struct gpio_desc *scl, struct gpio_desc *sda,
178 i2c_gpio_sda_high(scl, sda, delay);
180 for (j = 0; j < 8; j++) {
182 data |= i2c_gpio_read_bit(scl, sda, delay);
184 i2c_gpio_send_ack(scl, sda, delay, ack);
189 /* send start and the slave chip address */
190 int i2c_send_slave_addr(struct gpio_desc *scl, struct gpio_desc *sda, int delay,
193 i2c_gpio_send_start(scl, sda, delay);
195 if (i2c_gpio_write_byte(scl, sda, delay, chip)) {
196 i2c_gpio_send_stop(scl, sda, delay);
203 static int i2c_gpio_write_data(struct i2c_gpio_bus *bus, uchar chip,
204 uchar *buffer, int len,
205 bool end_with_repeated_start)
207 struct gpio_desc *scl = &bus->gpios[PIN_SCL];
208 struct gpio_desc *sda = &bus->gpios[PIN_SDA];
209 unsigned int delay = bus->udelay;
212 debug("%s: chip %x buffer %p len %d\n", __func__, chip, buffer, len);
214 if (i2c_send_slave_addr(scl, sda, delay, chip << 1)) {
215 debug("i2c_write, no chip responded %02X\n", chip);
220 if (i2c_gpio_write_byte(scl, sda, delay, *buffer++))
224 if (!end_with_repeated_start) {
225 i2c_gpio_send_stop(scl, sda, delay);
229 if (i2c_send_slave_addr(scl, sda, delay, (chip << 1) | 0x1)) {
230 debug("i2c_write, no chip responded %02X\n", chip);
237 static int i2c_gpio_read_data(struct i2c_gpio_bus *bus, uchar chip,
238 uchar *buffer, int len)
240 struct gpio_desc *scl = &bus->gpios[PIN_SCL];
241 struct gpio_desc *sda = &bus->gpios[PIN_SDA];
242 unsigned int delay = bus->udelay;
244 debug("%s: chip %x buffer: %p len %d\n", __func__, chip, buffer, len);
247 *buffer++ = i2c_gpio_read_byte(scl, sda, delay, len == 0);
249 i2c_gpio_send_stop(scl, sda, delay);
254 static int i2c_gpio_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
256 struct i2c_gpio_bus *bus = dev_get_priv(dev);
259 for (; nmsgs > 0; nmsgs--, msg++) {
260 bool next_is_read = nmsgs > 1 && (msg[1].flags & I2C_M_RD);
262 if (msg->flags & I2C_M_RD) {
263 ret = i2c_gpio_read_data(bus, msg->addr, msg->buf,
266 ret = i2c_gpio_write_data(bus, msg->addr, msg->buf,
267 msg->len, next_is_read);
277 static int i2c_gpio_probe(struct udevice *dev, uint chip, uint chip_flags)
279 struct i2c_gpio_bus *bus = dev_get_priv(dev);
280 struct gpio_desc *scl = &bus->gpios[PIN_SCL];
281 struct gpio_desc *sda = &bus->gpios[PIN_SDA];
282 unsigned int delay = bus->udelay;
285 i2c_gpio_send_start(scl, sda, delay);
286 ret = i2c_gpio_write_byte(scl, sda, delay, (chip << 1) | 0);
287 i2c_gpio_send_stop(scl, sda, delay);
289 debug("%s: bus: %d (%s) chip: %x flags: %x ret: %d\n",
290 __func__, dev->seq, dev->name, chip, chip_flags, ret);
295 static int i2c_gpio_set_bus_speed(struct udevice *dev, unsigned int speed_hz)
297 struct i2c_gpio_bus *bus = dev_get_priv(dev);
298 struct gpio_desc *scl = &bus->gpios[PIN_SCL];
299 struct gpio_desc *sda = &bus->gpios[PIN_SDA];
301 bus->udelay = 1000000 / (speed_hz << 2);
303 i2c_gpio_send_reset(scl, sda, bus->udelay);
308 static int i2c_gpio_ofdata_to_platdata(struct udevice *dev)
310 struct i2c_gpio_bus *bus = dev_get_priv(dev);
311 const void *blob = gd->fdt_blob;
312 int node = dev_of_offset(dev);
315 ret = gpio_request_list_by_name(dev, "gpios", bus->gpios,
316 ARRAY_SIZE(bus->gpios), 0);
320 bus->udelay = fdtdec_get_int(blob, node, "i2c-gpio,delay-us",
325 pr_err("Can't get %s gpios! Error: %d", dev->name, ret);
329 static const struct dm_i2c_ops i2c_gpio_ops = {
330 .xfer = i2c_gpio_xfer,
331 .probe_chip = i2c_gpio_probe,
332 .set_bus_speed = i2c_gpio_set_bus_speed,
335 static const struct udevice_id i2c_gpio_ids[] = {
336 { .compatible = "i2c-gpio" },
340 U_BOOT_DRIVER(i2c_gpio) = {
343 .of_match = i2c_gpio_ids,
344 .ofdata_to_platdata = i2c_gpio_ofdata_to_platdata,
345 .priv_auto_alloc_size = sizeof(struct i2c_gpio_bus),
346 .ops = &i2c_gpio_ops,