--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Congatec Board Controller I2C busses driver
+ *
+ * Copyright (C) 2024 Bootlin
+ * Author: Thomas Richard <thomas.richard@bootlin.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/iopoll.h>
+#include <linux/mfd/cgbc.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define CGBC_I2C_PRIMARY_BUS_ID 0
+#define CGBC_I2C_PM_BUS_ID 4
+
+#define CGBC_I2C_CMD_START 0x40
+#define CGBC_I2C_CMD_STAT 0x48
+#define CGBC_I2C_CMD_DATA 0x50
+#define CGBC_I2C_CMD_SPEED 0x58
+
+#define CGBC_I2C_STAT_IDL 0x00
+#define CGBC_I2C_STAT_DAT 0x01
+#define CGBC_I2C_STAT_BUSY 0x02
+
+#define CGBC_I2C_START 0x80
+#define CGBC_I2C_STOP 0x40
+
+#define CGBC_I2C_LAST_ACK 0x80 /* send ACK on last read byte */
+
+/*
+ * Reference code defines 1kHz as min freq and 6.1MHz as max freq.
+ * But in practice, the board controller limits the frequency to 1MHz, and the
+ * 1kHz is not functional (minimal working freq is 50kHz).
+ * So use these values as limits.
+ */
+#define CGBC_I2C_FREQ_MIN_HZ 50000 /* 50 kHz */
+#define CGBC_I2C_FREQ_MAX_HZ 1000000 /* 1 MHz */
+
+#define CGBC_I2C_FREQ_UNIT_1KHZ 0x40
+#define CGBC_I2C_FREQ_UNIT_10KHZ 0x80
+#define CGBC_I2C_FREQ_UNIT_100KHZ 0xC0
+
+#define CGBC_I2C_FREQ_UNIT_MASK 0xC0
+#define CGBC_I2C_FREQ_VALUE_MASK 0x3F
+
+#define CGBC_I2C_READ_MAX_LEN 31
+#define CGBC_I2C_WRITE_MAX_LEN 32
+
+#define CGBC_I2C_CMD_HEADER_SIZE 4
+#define CGBC_I2C_CMD_SIZE (CGBC_I2C_CMD_HEADER_SIZE + CGBC_I2C_WRITE_MAX_LEN)
+
+enum cgbc_i2c_state {
+ CGBC_I2C_STATE_DONE = 0,
+ CGBC_I2C_STATE_INIT,
+ CGBC_I2C_STATE_START,
+ CGBC_I2C_STATE_READ,
+ CGBC_I2C_STATE_WRITE,
+ CGBC_I2C_STATE_ERROR,
+};
+
+struct i2c_algo_cgbc_data {
+ u8 bus_id;
+ unsigned long read_maxtime_us;
+};
+
+struct cgbc_i2c_data {
+ struct device *dev;
+ struct cgbc_device_data *cgbc;
+ struct i2c_adapter adap;
+ struct i2c_msg *msg;
+ int nmsgs;
+ int pos;
+ enum cgbc_i2c_state state;
+};
+
+struct cgbc_i2c_transfer {
+ u8 bus_id;
+ bool start;
+ bool stop;
+ bool last_ack;
+ u8 read;
+ u8 write;
+ u8 addr;
+ u8 data[CGBC_I2C_WRITE_MAX_LEN];
+};
+
+static u8 cgbc_i2c_freq_to_reg(unsigned int bus_frequency)
+{
+ u8 reg;
+
+ if (bus_frequency <= 10000)
+ reg = CGBC_I2C_FREQ_UNIT_1KHZ | (bus_frequency / 1000);
+ else if (bus_frequency <= 100000)
+ reg = CGBC_I2C_FREQ_UNIT_10KHZ | (bus_frequency / 10000);
+ else
+ reg = CGBC_I2C_FREQ_UNIT_100KHZ | (bus_frequency / 100000);
+
+ return reg;
+}
+
+static unsigned int cgbc_i2c_reg_to_freq(u8 reg)
+{
+ unsigned int freq = reg & CGBC_I2C_FREQ_VALUE_MASK;
+ u8 unit = reg & CGBC_I2C_FREQ_UNIT_MASK;
+
+ if (unit == CGBC_I2C_FREQ_UNIT_100KHZ)
+ return freq * 100000;
+ else if (unit == CGBC_I2C_FREQ_UNIT_10KHZ)
+ return freq * 10000;
+ else
+ return freq * 1000;
+}
+
+static int cgbc_i2c_get_status(struct i2c_adapter *adap)
+{
+ struct i2c_algo_cgbc_data *algo_data = adap->algo_data;
+ struct cgbc_i2c_data *i2c = i2c_get_adapdata(adap);
+ struct cgbc_device_data *cgbc = i2c->cgbc;
+ u8 cmd = CGBC_I2C_CMD_STAT | algo_data->bus_id;
+ u8 status;
+ int ret;
+
+ ret = cgbc_command(cgbc, &cmd, sizeof(cmd), NULL, 0, &status);
+ if (ret)
+ return ret;
+
+ return status;
+}
+
+static int cgbc_i2c_set_frequency(struct i2c_adapter *adap,
+ unsigned int bus_frequency)
+{
+ struct i2c_algo_cgbc_data *algo_data = adap->algo_data;
+ struct cgbc_i2c_data *i2c = i2c_get_adapdata(adap);
+ struct cgbc_device_data *cgbc = i2c->cgbc;
+ u8 cmd[2], data;
+ int ret;
+
+ if (bus_frequency > CGBC_I2C_FREQ_MAX_HZ ||
+ bus_frequency < CGBC_I2C_FREQ_MIN_HZ) {
+ dev_info(i2c->dev, "invalid frequency %u, using default\n", bus_frequency);
+ bus_frequency = I2C_MAX_STANDARD_MODE_FREQ;
+ }
+
+ cmd[0] = CGBC_I2C_CMD_SPEED | algo_data->bus_id;
+ cmd[1] = cgbc_i2c_freq_to_reg(bus_frequency);
+
+ ret = cgbc_command(cgbc, &cmd, sizeof(cmd), &data, 1, NULL);
+ if (ret)
+ return dev_err_probe(i2c->dev, ret,
+ "Failed to initialize I2C bus %s",
+ adap->name);
+
+ cmd[1] = 0x00;
+
+ ret = cgbc_command(cgbc, &cmd, sizeof(cmd), &data, 1, NULL);
+ if (ret)
+ return dev_err_probe(i2c->dev, ret,
+ "Failed to get I2C bus frequency");
+
+ bus_frequency = cgbc_i2c_reg_to_freq(data);
+
+ dev_dbg(i2c->dev, "%s is running at %d Hz\n", adap->name, bus_frequency);
+
+ /*
+ * The read_maxtime_us variable represents the maximum time to wait
+ * for data during a read operation. The maximum amount of data that
+ * can be read by a command is CGBC_I2C_READ_MAX_LEN.
+ * Therefore, calculate the max time to properly size the timeout.
+ */
+ algo_data->read_maxtime_us = (BITS_PER_BYTE + 1) * CGBC_I2C_READ_MAX_LEN
+ * USEC_PER_SEC / bus_frequency;
+
+ return 0;
+}
+
+static unsigned int cgbc_i2c_xfer_to_cmd(struct cgbc_i2c_transfer xfer, u8 *cmd)
+{
+ int i = 0;
+
+ cmd[i++] = CGBC_I2C_CMD_START | xfer.bus_id;
+
+ cmd[i] = (xfer.start) ? CGBC_I2C_START : 0x00;
+ if (xfer.stop)
+ cmd[i] |= CGBC_I2C_STOP;
+ cmd[i++] |= (xfer.start) ? xfer.write + 1 : xfer.write;
+
+ cmd[i++] = (xfer.last_ack) ? (xfer.read | CGBC_I2C_LAST_ACK) : xfer.read;
+
+ if (xfer.start)
+ cmd[i++] = xfer.addr;
+
+ if (xfer.write > 0)
+ memcpy(&cmd[i], &xfer.data, xfer.write);
+
+ return i + xfer.write;
+}
+
+static int cgbc_i2c_xfer_msg(struct i2c_adapter *adap)
+{
+ struct i2c_algo_cgbc_data *algo_data = adap->algo_data;
+ struct cgbc_i2c_data *i2c = i2c_get_adapdata(adap);
+ struct cgbc_device_data *cgbc = i2c->cgbc;
+ struct i2c_msg *msg = i2c->msg;
+ u8 cmd[CGBC_I2C_CMD_SIZE];
+ int ret, max_len, len, i;
+ unsigned int cmd_len;
+ u8 cmd_data;
+
+ struct cgbc_i2c_transfer xfer = {
+ .bus_id = algo_data->bus_id,
+ .addr = i2c_8bit_addr_from_msg(msg),
+ };
+
+ if (i2c->state == CGBC_I2C_STATE_DONE)
+ return 0;
+
+ ret = cgbc_i2c_get_status(adap);
+
+ if (ret == CGBC_I2C_STAT_BUSY)
+ return -EBUSY;
+ else if (ret < 0)
+ goto err;
+
+ if (i2c->state == CGBC_I2C_STATE_INIT ||
+ (i2c->state == CGBC_I2C_STATE_WRITE && msg->flags & I2C_M_RD))
+ xfer.start = true;
+
+ i2c->state = (msg->flags & I2C_M_RD) ? CGBC_I2C_STATE_READ : CGBC_I2C_STATE_WRITE;
+
+ max_len = (i2c->state == CGBC_I2C_STATE_READ) ?
+ CGBC_I2C_READ_MAX_LEN : CGBC_I2C_WRITE_MAX_LEN;
+
+ if (msg->len - i2c->pos > max_len) {
+ len = max_len;
+ } else {
+ len = msg->len - i2c->pos;
+
+ if (i2c->nmsgs == 1)
+ xfer.stop = true;
+ }
+
+ if (i2c->state == CGBC_I2C_STATE_WRITE) {
+ xfer.write = len;
+ xfer.read = 0;
+
+ for (i = 0; i < len; i++)
+ xfer.data[i] = msg->buf[i2c->pos + i];
+
+ cmd_len = cgbc_i2c_xfer_to_cmd(xfer, &cmd[0]);
+
+ ret = cgbc_command(cgbc, &cmd, cmd_len, NULL, 0, NULL);
+ if (ret)
+ goto err;
+ } else if (i2c->state == CGBC_I2C_STATE_READ) {
+ xfer.write = 0;
+ xfer.read = len;
+
+ if (i2c->nmsgs > 1 || msg->len - i2c->pos > max_len)
+ xfer.read |= CGBC_I2C_LAST_ACK;
+
+ cmd_len = cgbc_i2c_xfer_to_cmd(xfer, &cmd[0]);
+ ret = cgbc_command(cgbc, &cmd, cmd_len, NULL, 0, NULL);
+ if (ret)
+ goto err;
+
+ ret = read_poll_timeout(cgbc_i2c_get_status, ret,
+ ret != CGBC_I2C_STAT_BUSY, 0,
+ 2 * algo_data->read_maxtime_us, false, adap);
+ if (ret < 0)
+ goto err;
+
+ cmd_data = CGBC_I2C_CMD_DATA | algo_data->bus_id;
+ ret = cgbc_command(cgbc, &cmd_data, sizeof(cmd_data),
+ msg->buf + i2c->pos, len, NULL);
+ if (ret)
+ goto err;
+ }
+
+ if (len == (msg->len - i2c->pos)) {
+ i2c->msg++;
+ i2c->nmsgs--;
+ i2c->pos = 0;
+ } else {
+ i2c->pos += len;
+ }
+
+ if (i2c->nmsgs == 0)
+ i2c->state = CGBC_I2C_STATE_DONE;
+
+ return 0;
+
+err:
+ i2c->state = CGBC_I2C_STATE_ERROR;
+ return ret;
+}
+
+static int cgbc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ struct cgbc_i2c_data *i2c = i2c_get_adapdata(adap);
+ unsigned long timeout = jiffies + HZ;
+ int ret;
+
+ i2c->state = CGBC_I2C_STATE_INIT;
+ i2c->msg = msgs;
+ i2c->nmsgs = num;
+ i2c->pos = 0;
+
+ while (time_before(jiffies, timeout)) {
+ ret = cgbc_i2c_xfer_msg(adap);
+ if (i2c->state == CGBC_I2C_STATE_DONE)
+ return num;
+
+ if (i2c->state == CGBC_I2C_STATE_ERROR)
+ return ret;
+
+ if (ret == 0)
+ timeout = jiffies + HZ;
+ }
+
+ i2c->state = CGBC_I2C_STATE_ERROR;
+ return -ETIMEDOUT;
+}
+
+static u32 cgbc_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~(I2C_FUNC_SMBUS_QUICK));
+}
+
+static const struct i2c_algorithm cgbc_i2c_algorithm = {
+ .master_xfer = cgbc_i2c_xfer,
+ .functionality = cgbc_i2c_func,
+};
+
+static struct i2c_algo_cgbc_data cgbc_i2c_algo_data[] = {
+ { .bus_id = CGBC_I2C_PRIMARY_BUS_ID },
+ { .bus_id = CGBC_I2C_PM_BUS_ID },
+};
+
+static const struct i2c_adapter cgbc_i2c_adapter[] = {
+ {
+ .owner = THIS_MODULE,
+ .name = "Congatec General Purpose I2C adapter",
+ .class = I2C_CLASS_DEPRECATED,
+ .algo = &cgbc_i2c_algorithm,
+ .algo_data = &cgbc_i2c_algo_data[0],
+ .nr = -1,
+ },
+ {
+ .owner = THIS_MODULE,
+ .name = "Congatec Power Management I2C adapter",
+ .class = I2C_CLASS_DEPRECATED,
+ .algo = &cgbc_i2c_algorithm,
+ .algo_data = &cgbc_i2c_algo_data[1],
+ .nr = -1,
+ },
+};
+
+static int cgbc_i2c_probe(struct platform_device *pdev)
+{
+ struct cgbc_device_data *cgbc = dev_get_drvdata(pdev->dev.parent);
+ struct cgbc_i2c_data *i2c;
+ int ret;
+
+ i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
+ if (!i2c)
+ return -ENOMEM;
+
+ i2c->cgbc = cgbc;
+ i2c->dev = &pdev->dev;
+ i2c->adap = cgbc_i2c_adapter[pdev->id];
+ i2c->adap.dev.parent = i2c->dev;
+ i2c_set_adapdata(&i2c->adap, i2c);
+ platform_set_drvdata(pdev, i2c);
+
+ ret = cgbc_i2c_set_frequency(&i2c->adap, I2C_MAX_STANDARD_MODE_FREQ);
+ if (ret)
+ return ret;
+
+ return i2c_add_numbered_adapter(&i2c->adap);
+}
+
+static void cgbc_i2c_remove(struct platform_device *pdev)
+{
+ struct cgbc_i2c_data *i2c = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&i2c->adap);
+}
+
+static struct platform_driver cgbc_i2c_driver = {
+ .driver = {
+ .name = "cgbc-i2c",
+ },
+ .probe = cgbc_i2c_probe,
+ .remove_new = cgbc_i2c_remove,
+};
+
+module_platform_driver(cgbc_i2c_driver);
+
+MODULE_DESCRIPTION("Congatec Board Controller I2C Driver");
+MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:cgbc_i2c");
projects / linux-2.6-microblaze.git / commitdiff