--- /dev/null
+/*
+ * I2C bus driver for Amlogic Meson SoCs
+ *
+ * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
+ *
+ * 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/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>
+#include <linux/types.h>
+
+/* Meson I2C register map */
+#define REG_CTRL 0x00
+#define REG_SLAVE_ADDR 0x04
+#define REG_TOK_LIST0 0x08
+#define REG_TOK_LIST1 0x0c
+#define REG_TOK_WDATA0 0x10
+#define REG_TOK_WDATA1 0x14
+#define REG_TOK_RDATA0 0x18
+#define REG_TOK_RDATA1 0x1c
+
+/* Control register fields */
+#define REG_CTRL_START BIT(0)
+#define REG_CTRL_ACK_IGNORE BIT(1)
+#define REG_CTRL_STATUS BIT(2)
+#define REG_CTRL_ERROR BIT(3)
+#define REG_CTRL_CLKDIV_SHIFT 12
+#define REG_CTRL_CLKDIV_MASK ((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
+
+#define I2C_TIMEOUT_MS 500
+#define DEFAULT_FREQ 100000
+
+enum {
+ TOKEN_END = 0,
+ TOKEN_START,
+ TOKEN_SLAVE_ADDR_WRITE,
+ TOKEN_SLAVE_ADDR_READ,
+ TOKEN_DATA,
+ TOKEN_DATA_LAST,
+ TOKEN_STOP,
+};
+
+enum {
+ STATE_IDLE,
+ STATE_READ,
+ STATE_WRITE,
+ STATE_STOP,
+};
+
+/**
+ * struct meson_i2c - Meson I2C device private data
+ *
+ * @adap: I2C adapter instance
+ * @dev: Pointer to device structure
+ * @regs: Base address of the device memory mapped registers
+ * @clk: Pointer to clock structure
+ * @irq: IRQ number
+ * @msg: Pointer to the current I2C message
+ * @state: Current state in the driver state machine
+ * @last: Flag set for the last message in the transfer
+ * @count: Number of bytes to be sent/received in current transfer
+ * @pos: Current position in the send/receive buffer
+ * @error: Flag set when an error is received
+ * @lock: To avoid race conditions between irq handler and xfer code
+ * @done: Completion used to wait for transfer termination
+ * @frequency: Operating frequency of I2C bus clock
+ * @tokens: Sequence of tokens to be written to the device
+ * @num_tokens: Number of tokens
+ */
+struct meson_i2c {
+ struct i2c_adapter adap;
+ struct device *dev;
+ void __iomem *regs;
+ struct clk *clk;
+ int irq;
+
+ struct i2c_msg *msg;
+ int state;
+ bool last;
+ int count;
+ int pos;
+ int error;
+
+ spinlock_t lock;
+ struct completion done;
+ unsigned int frequency;
+ u32 tokens[2];
+ int num_tokens;
+};
+
+static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask,
+ u32 val)
+{
+ u32 data;
+
+ data = readl(i2c->regs + reg);
+ data &= ~mask;
+ data |= val & mask;
+ writel(data, i2c->regs + reg);
+}
+
+static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
+{
+ i2c->tokens[0] = 0;
+ i2c->tokens[1] = 0;
+ i2c->num_tokens = 0;
+}
+
+static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
+{
+ if (i2c->num_tokens < 8)
+ i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
+ else
+ i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
+
+ i2c->num_tokens++;
+}
+
+static void meson_i2c_write_tokens(struct meson_i2c *i2c)
+{
+ writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
+ writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
+}
+
+static void meson_i2c_set_clk_div(struct meson_i2c *i2c)
+{
+ unsigned long clk_rate = clk_get_rate(i2c->clk);
+ unsigned int div;
+
+ div = DIV_ROUND_UP(clk_rate, i2c->frequency * 4);
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
+ div << REG_CTRL_CLKDIV_SHIFT);
+
+ dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
+ clk_rate, i2c->frequency, div);
+}
+
+static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
+{
+ u32 rdata0, rdata1;
+ int i;
+
+ rdata0 = readl(i2c->regs + REG_TOK_RDATA0);
+ rdata1 = readl(i2c->regs + REG_TOK_RDATA1);
+
+ dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
+ rdata0, rdata1, len);
+
+ for (i = 0; i < min_t(int, 4, len); i++)
+ *buf++ = (rdata0 >> i * 8) & 0xff;
+
+ for (i = 4; i < min_t(int, 8, len); i++)
+ *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
+}
+
+static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
+{
+ u32 wdata0 = 0, wdata1 = 0;
+ int i;
+
+ for (i = 0; i < min_t(int, 4, len); i++)
+ wdata0 |= *buf++ << (i * 8);
+
+ for (i = 4; i < min_t(int, 8, len); i++)
+ wdata1 |= *buf++ << ((i - 4) * 8);
+
+ writel(wdata0, i2c->regs + REG_TOK_WDATA0);
+ writel(wdata0, i2c->regs + REG_TOK_WDATA1);
+
+ dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
+ wdata0, wdata1, len);
+}
+
+static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
+{
+ bool write = !(i2c->msg->flags & I2C_M_RD);
+ int i;
+
+ i2c->count = min_t(int, i2c->msg->len - i2c->pos, 8);
+
+ for (i = 0; i < i2c->count - 1; i++)
+ meson_i2c_add_token(i2c, TOKEN_DATA);
+
+ if (i2c->count) {
+ if (write || i2c->pos + i2c->count < i2c->msg->len)
+ meson_i2c_add_token(i2c, TOKEN_DATA);
+ else
+ meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
+ }
+
+ if (write)
+ meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
+}
+
+static void meson_i2c_stop(struct meson_i2c *i2c)
+{
+ dev_dbg(i2c->dev, "%s: last %d\n", __func__, i2c->last);
+
+ if (i2c->last) {
+ i2c->state = STATE_STOP;
+ meson_i2c_add_token(i2c, TOKEN_STOP);
+ } else {
+ i2c->state = STATE_IDLE;
+ complete_all(&i2c->done);
+ }
+}
+
+static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
+{
+ struct meson_i2c *i2c = dev_id;
+ unsigned int ctrl;
+
+ spin_lock(&i2c->lock);
+
+ meson_i2c_reset_tokens(i2c);
+ ctrl = readl(i2c->regs + REG_CTRL);
+
+ dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
+ i2c->state, i2c->pos, i2c->count, ctrl);
+
+ if (ctrl & REG_CTRL_ERROR && i2c->state != STATE_IDLE) {
+ /*
+ * The bit is set when the IGNORE_NAK bit is cleared
+ * and the device didn't respond. In this case, the
+ * I2C controller automatically generates a STOP
+ * condition.
+ */
+ dev_dbg(i2c->dev, "error bit set\n");
+ i2c->error = -ENXIO;
+ i2c->state = STATE_IDLE;
+ complete_all(&i2c->done);
+ goto out;
+ }
+
+ switch (i2c->state) {
+ case STATE_READ:
+ if (i2c->count > 0) {
+ meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
+ i2c->count);
+ i2c->pos += i2c->count;
+ }
+
+ if (i2c->pos >= i2c->msg->len) {
+ meson_i2c_stop(i2c);
+ break;
+ }
+
+ meson_i2c_prepare_xfer(i2c);
+ break;
+ case STATE_WRITE:
+ i2c->pos += i2c->count;
+
+ if (i2c->pos >= i2c->msg->len) {
+ meson_i2c_stop(i2c);
+ break;
+ }
+
+ meson_i2c_prepare_xfer(i2c);
+ break;
+ case STATE_STOP:
+ i2c->state = STATE_IDLE;
+ complete_all(&i2c->done);
+ break;
+ case STATE_IDLE:
+ break;
+ }
+
+out:
+ if (i2c->state != STATE_IDLE) {
+ /* Restart the processing */
+ meson_i2c_write_tokens(i2c);
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
+ REG_CTRL_START);
+ }
+
+ spin_unlock(&i2c->lock);
+
+ return IRQ_HANDLED;
+}
+
+static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
+{
+ int token;
+
+ token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
+ TOKEN_SLAVE_ADDR_WRITE;
+
+ writel(msg->addr << 1, i2c->regs + REG_SLAVE_ADDR);
+ meson_i2c_add_token(i2c, TOKEN_START);
+ meson_i2c_add_token(i2c, token);
+}
+
+static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
+ int last)
+{
+ unsigned long time_left, flags;
+ int ret = 0;
+
+ i2c->msg = msg;
+ i2c->last = last;
+ i2c->pos = 0;
+ i2c->count = 0;
+ i2c->error = 0;
+
+ meson_i2c_reset_tokens(i2c);
+
+ flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0;
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags);
+
+ if (!(msg->flags & I2C_M_NOSTART))
+ meson_i2c_do_start(i2c, msg);
+
+ i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
+ meson_i2c_prepare_xfer(i2c);
+ meson_i2c_write_tokens(i2c);
+ reinit_completion(&i2c->done);
+
+ /* Start the transfer */
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
+
+ time_left = msecs_to_jiffies(I2C_TIMEOUT_MS);
+ time_left = wait_for_completion_timeout(&i2c->done, time_left);
+
+ /*
+ * Protect access to i2c struct and registers from interrupt
+ * handlers triggered by a transfer terminated after the
+ * timeout period
+ */
+ spin_lock_irqsave(&i2c->lock, flags);
+
+ /* Abort any active operation */
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
+
+ if (!time_left) {
+ i2c->state = STATE_IDLE;
+ ret = -ETIMEDOUT;
+ }
+
+ if (i2c->error)
+ ret = i2c->error;
+
+ spin_unlock_irqrestore(&i2c->lock, flags);
+
+ return ret;
+}
+
+static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ struct meson_i2c *i2c = adap->algo_data;
+ int i, ret = 0, count = 0;
+
+ clk_enable(i2c->clk);
+ meson_i2c_set_clk_div(i2c);
+
+ for (i = 0; i < num; i++) {
+ ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
+ if (ret)
+ break;
+ count++;
+ }
+
+ clk_disable(i2c->clk);
+
+ return ret ? ret : count;
+}
+
+static u32 meson_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm meson_i2c_algorithm = {
+ .master_xfer = meson_i2c_xfer,
+ .functionality = meson_i2c_func,
+};
+
+static int meson_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct meson_i2c *i2c;
+ struct resource *mem;
+ int ret = 0;
+
+ i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_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)) {
+ dev_err(&pdev->dev, "can't get device clock\n");
+ return PTR_ERR(i2c->clk);
+ }
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
+ if (IS_ERR(i2c->regs))
+ return PTR_ERR(i2c->regs);
+
+ i2c->irq = platform_get_irq(pdev, 0);
+ if (i2c->irq < 0) {
+ dev_err(&pdev->dev, "can't find IRQ\n");
+ return i2c->irq;
+ }
+
+ ret = devm_request_irq(&pdev->dev, i2c->irq, meson_i2c_irq,
+ 0, dev_name(&pdev->dev), i2c);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "can't request IRQ\n");
+ return ret;
+ }
+
+ ret = clk_prepare(i2c->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "can't prepare clock\n");
+ return ret;
+ }
+
+ strlcpy(i2c->adap.name, "Meson I2C adapter",
+ sizeof(i2c->adap.name));
+ i2c->adap.owner = THIS_MODULE;
+ i2c->adap.algo = &meson_i2c_algorithm;
+ i2c->adap.dev.parent = &pdev->dev;
+ i2c->adap.dev.of_node = np;
+ i2c->adap.algo_data = i2c;
+
+ /*
+ * A transfer is triggered when START bit changes from 0 to 1.
+ * Ensure that the bit is set to 0 after probe
+ */
+ meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
+
+ ret = i2c_add_adapter(&i2c->adap);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "can't register adapter\n");
+ clk_unprepare(i2c->clk);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int meson_i2c_remove(struct platform_device *pdev)
+{
+ struct meson_i2c *i2c = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&i2c->adap);
+ clk_unprepare(i2c->clk);
+
+ return 0;
+}
+
+static const struct of_device_id meson_i2c_match[] = {
+ { .compatible = "amlogic,meson6-i2c" },
+ { },
+};
+
+static struct platform_driver meson_i2c_driver = {
+ .probe = meson_i2c_probe,
+ .remove = meson_i2c_remove,
+ .driver = {
+ .name = "meson-i2c",
+ .of_match_table = meson_i2c_match,
+ },
+};
+
+module_platform_driver(meson_i2c_driver);
+
+MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver");
+MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
+MODULE_LICENSE("GPL v2");
projects / deliverable / linux.git / commitdiff
