--- /dev/null
+/*
+ * I2C bus driver for Conexant Digicolor SoCs
+ *
+ * Author: Baruch Siach <baruch@tkos.co.il>
+ *
+ * Copyright (C) 2015 Paradox Innovation Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#define DEFAULT_FREQ 100000
+#define TIMEOUT_MS 100
+
+#define II_CONTROL 0x0
+#define II_CONTROL_LOCAL_RESET BIT(0)
+
+#define II_CLOCKTIME 0x1
+
+#define II_COMMAND 0x2
+#define II_CMD_START 1
+#define II_CMD_RESTART 2
+#define II_CMD_SEND_ACK 3
+#define II_CMD_GET_ACK 6
+#define II_CMD_GET_NOACK 7
+#define II_CMD_STOP 10
+#define II_COMMAND_GO BIT(7)
+#define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3)
+#define II_CMD_STATUS_NORMAL 0
+#define II_CMD_STATUS_ACK_GOOD 1
+#define II_CMD_STATUS_ACK_BAD 2
+#define II_CMD_STATUS_ABORT 3
+
+#define II_DATA 0x3
+#define II_INTFLAG_CLEAR 0x8
+#define II_INTENABLE 0xa
+
+struct dc_i2c {
+ struct i2c_adapter adap;
+ struct device *dev;
+ void __iomem *regs;
+ struct clk *clk;
+ unsigned int frequency;
+
+ struct i2c_msg *msg;
+ unsigned int msgbuf_ptr;
+ int last;
+ spinlock_t lock;
+ struct completion done;
+ int state;
+ int error;
+};
+
+enum {
+ STATE_IDLE,
+ STATE_START,
+ STATE_ADDR,
+ STATE_WRITE,
+ STATE_READ,
+ STATE_STOP,
+};
+
+static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
+{
+ writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
+}
+
+static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
+{
+ u8 addr = (msg->addr & 0x7f) << 1;
+
+ if (msg->flags & I2C_M_RD)
+ addr |= 1;
+
+ return addr;
+}
+
+static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
+{
+ writeb_relaxed(data, i2c->regs + II_DATA);
+}
+
+static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
+{
+ dc_i2c_data(i2c, byte);
+ dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
+}
+
+static void dc_i2c_write_buf(struct dc_i2c *i2c)
+{
+ dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
+}
+
+static void dc_i2c_next_read(struct dc_i2c *i2c)
+{
+ bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);
+
+ dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
+}
+
+static void dc_i2c_stop(struct dc_i2c *i2c)
+{
+ i2c->state = STATE_STOP;
+ if (i2c->last)
+ dc_i2c_cmd(i2c, II_CMD_STOP);
+ else
+ complete(&i2c->done);
+}
+
+static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
+{
+ return readb_relaxed(i2c->regs + II_DATA);
+}
+
+static void dc_i2c_read_buf(struct dc_i2c *i2c)
+{
+ i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
+ dc_i2c_next_read(i2c);
+}
+
+static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
+{
+ if (enable)
+ writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
+ writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
+}
+
+static int dc_i2c_cmd_status(struct dc_i2c *i2c)
+{
+ u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);
+
+ return II_COMMAND_COMPLETION_STATUS(cmd);
+}
+
+static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
+{
+ struct i2c_msg *msg = i2c->msg;
+
+ if (!(msg->flags & I2C_M_NOSTART)) {
+ i2c->state = STATE_START;
+ dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
+ } else if (msg->flags & I2C_M_RD) {
+ i2c->state = STATE_READ;
+ dc_i2c_next_read(i2c);
+ } else {
+ i2c->state = STATE_WRITE;
+ dc_i2c_write_buf(i2c);
+ }
+}
+
+static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
+{
+ struct dc_i2c *i2c = dev_id;
+ int cmd_status = dc_i2c_cmd_status(i2c);
+ unsigned long flags;
+ u8 addr_cmd;
+
+ writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
+
+ spin_lock_irqsave(&i2c->lock, flags);
+
+ if (cmd_status == II_CMD_STATUS_ACK_BAD
+ || cmd_status == II_CMD_STATUS_ABORT) {
+ i2c->error = -EIO;
+ complete(&i2c->done);
+ goto out;
+ }
+
+ switch (i2c->state) {
+ case STATE_START:
+ addr_cmd = dc_i2c_addr_cmd(i2c->msg);
+ dc_i2c_write_byte(i2c, addr_cmd);
+ i2c->state = STATE_ADDR;
+ break;
+ case STATE_ADDR:
+ if (i2c->msg->flags & I2C_M_RD) {
+ dc_i2c_next_read(i2c);
+ i2c->state = STATE_READ;
+ break;
+ }
+ i2c->state = STATE_WRITE;
+ /* fall through */
+ case STATE_WRITE:
+ if (i2c->msgbuf_ptr < i2c->msg->len)
+ dc_i2c_write_buf(i2c);
+ else
+ dc_i2c_stop(i2c);
+ break;
+ case STATE_READ:
+ if (i2c->msgbuf_ptr < i2c->msg->len)
+ dc_i2c_read_buf(i2c);
+ else
+ dc_i2c_stop(i2c);
+ break;
+ case STATE_STOP:
+ i2c->state = STATE_IDLE;
+ complete(&i2c->done);
+ break;
+ }
+
+out:
+ spin_unlock_irqrestore(&i2c->lock, flags);
+ return IRQ_HANDLED;
+}
+
+static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
+ int last)
+{
+ unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS);
+ unsigned long flags;
+
+ spin_lock_irqsave(&i2c->lock, flags);
+ i2c->msg = msg;
+ i2c->msgbuf_ptr = 0;
+ i2c->last = last;
+ i2c->error = 0;
+
+ reinit_completion(&i2c->done);
+ dc_i2c_set_irq(i2c, 1);
+ dc_i2c_start_msg(i2c, first);
+ spin_unlock_irqrestore(&i2c->lock, flags);
+
+ timeout = wait_for_completion_timeout(&i2c->done, timeout);
+ dc_i2c_set_irq(i2c, 0);
+ if (timeout == 0) {
+ i2c->state = STATE_IDLE;
+ return -ETIMEDOUT;
+ }
+
+ if (i2c->error)
+ return i2c->error;
+
+ return 0;
+}
+
+static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+ struct dc_i2c *i2c = adap->algo_data;
+ int i, ret;
+
+ for (i = 0; i < num; i++) {
+ ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
+ if (ret)
+ return ret;
+ }
+
+ return num;
+}
+
+static int dc_i2c_init_hw(struct dc_i2c *i2c)
+{
+ unsigned long clk_rate = clk_get_rate(i2c->clk);
+ unsigned int clocktime;
+
+ writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
+ udelay(100);
+ writeb_relaxed(0, i2c->regs + II_CONTROL);
+ udelay(100);
+
+ clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
+ if (clocktime < 1 || clocktime > 0xff) {
+ dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
+ i2c->frequency);
+ return -EINVAL;
+ }
+ writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME);
+
+ return 0;
+}
+
+static u32 dc_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
+}
+
+static const struct i2c_algorithm dc_i2c_algorithm = {
+ .master_xfer = dc_i2c_xfer,
+ .functionality = dc_i2c_func,
+};
+
+static int dc_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct dc_i2c *i2c;
+ struct resource *r;
+ int ret = 0, irq;
+
+ i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
+ if (!i2c)
+ return -ENOMEM;
+
+ if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+ &i2c->frequency))
+ i2c->frequency = DEFAULT_FREQ;
+
+ i2c->dev = &pdev->dev;
+ platform_set_drvdata(pdev, i2c);
+
+ spin_lock_init(&i2c->lock);
+ init_completion(&i2c->done);
+
+ i2c->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(i2c->clk))
+ return PTR_ERR(i2c->clk);
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ i2c->regs = devm_ioremap_resource(&pdev->dev, r);
+ if (IS_ERR(i2c->regs))
+ return PTR_ERR(i2c->regs);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
+ dev_name(&pdev->dev), i2c);
+ if (ret < 0)
+ return ret;
+
+ strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
+ sizeof(i2c->adap.name));
+ i2c->adap.owner = THIS_MODULE;
+ i2c->adap.algo = &dc_i2c_algorithm;
+ i2c->adap.dev.parent = &pdev->dev;
+ i2c->adap.dev.of_node = np;
+ i2c->adap.algo_data = i2c;
+
+ ret = dc_i2c_init_hw(i2c);
+ if (ret)
+ return ret;
+
+ ret = clk_prepare_enable(i2c->clk);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_add_adapter(&i2c->adap);
+ if (ret < 0) {
+ clk_unprepare(i2c->clk);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int dc_i2c_remove(struct platform_device *pdev)
+{
+ struct dc_i2c *i2c = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&i2c->adap);
+ clk_disable_unprepare(i2c->clk);
+
+ return 0;
+}
+
+static const struct of_device_id dc_i2c_match[] = {
+ { .compatible = "cnxt,cx92755-i2c" },
+ { },
+};
+
+static struct platform_driver dc_i2c_driver = {
+ .probe = dc_i2c_probe,
+ .remove = dc_i2c_remove,
+ .driver = {
+ .name = "digicolor-i2c",
+ .of_match_table = dc_i2c_match,
+ },
+};
+module_platform_driver(dc_i2c_driver);
+
+MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
+MODULE_DESCRIPTION("Conexant Digicolor I2C master driver");
+MODULE_LICENSE("GPL v2");
Code Review / kvmfornfv.git / blobdiff