i2c: add Amlogic Meson driver

Add a driver for the I2C controller available on Amlogic Meson SoCs.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

1 files changed, 263 insertions, 0 deletions

diff --git a/drivers/i2c/meson_i2c.c b/drivers/i2c/meson_i2c.c
new file mode 100644
index 0000000000..2434d9ed53
--- /dev/null
+++ b/drivers/i2c/meson_i2c.c
@@ -0,0 +1,263 @@
+/*
+ * (C) Copyright 2017 - Beniamino Galvani <b.galvani@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+#include <common.h>
+#include <asm/arch/i2c.h>
+#include <asm/io.h>
+#include <dm.h>
+#include <i2c.h>
+
+#define I2C_TIMEOUT_MS		500
+
+/* 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	GENMASK(21, 12)
+#define REG_CTRL_CLKDIVEXT_SHIFT 28
+#define REG_CTRL_CLKDIVEXT_MASK	GENMASK(29, 28)
+
+enum {
+	TOKEN_END = 0,
+	TOKEN_START,
+	TOKEN_SLAVE_ADDR_WRITE,
+	TOKEN_SLAVE_ADDR_READ,
+	TOKEN_DATA,
+	TOKEN_DATA_LAST,
+	TOKEN_STOP,
+};
+
+struct i2c_regs {
+	u32 ctrl;
+	u32 slave_addr;
+	u32 tok_list0;
+	u32 tok_list1;
+	u32 tok_wdata0;
+	u32 tok_wdata1;
+	u32 tok_rdata0;
+	u32 tok_rdata1;
+};
+
+struct meson_i2c {
+	struct i2c_regs *regs;
+	struct i2c_msg *msg;
+	bool last;
+	uint count;
+	uint pos;
+	u32 tokens[2];
+	uint num_tokens;
+};
+
+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_get_data(struct meson_i2c *i2c, u8 *buf, int len)
+{
+	u32 rdata0, rdata1;
+	int i;
+
+	rdata0 = readl(&i2c->regs->tok_rdata0);
+	rdata1 = readl(&i2c->regs->tok_rdata1);
+
+	debug("meson i2c: read data %08x %08x len %d\n", rdata0, rdata1, len);
+
+	for (i = 0; i < min(4, len); i++)
+		*buf++ = (rdata0 >> i * 8) & 0xff;
+
+	for (i = 4; i < min(8, len); i++)
+		*buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
+}
+
+static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
+{
+	u32 wdata0 = 0, wdata1 = 0;
+	int i;
+
+	for (i = 0; i < min(4, len); i++)
+		wdata0 |= *buf++ << (i * 8);
+
+	for (i = 4; i < min(8, len); i++)
+		wdata1 |= *buf++ << ((i - 4) * 8);
+
+	writel(wdata0, &i2c->regs->tok_wdata0);
+	writel(wdata1, &i2c->regs->tok_wdata1);
+
+	debug("meson i2c: write data %08x %08x len %d\n", 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(i2c->msg->len - i2c->pos, 8u);
+
+	for (i = 0; i + 1 < i2c->count; 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);
+
+	if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
+		meson_i2c_add_token(i2c, TOKEN_STOP);
+
+	writel(i2c->tokens[0], &i2c->regs->tok_list0);
+	writel(i2c->tokens[1], &i2c->regs->tok_list1);
+}
+
+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->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)
+{
+	ulong start;
+
+	debug("meson i2c: %s addr %u len %u\n",
+	      (msg->flags & I2C_M_RD) ? "read" : "write",
+	      msg->addr, msg->len);
+
+	i2c->msg = msg;
+	i2c->last = last;
+	i2c->pos = 0;
+	i2c->count = 0;
+
+	meson_i2c_reset_tokens(i2c);
+	meson_i2c_do_start(i2c, msg);
+
+	do {
+		meson_i2c_prepare_xfer(i2c);
+
+		/* start the transfer */
+		setbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
+		start = get_timer(0);
+		while (readl(&i2c->regs->ctrl) & REG_CTRL_STATUS) {
+			if (get_timer(start) > I2C_TIMEOUT_MS) {
+				clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
+				debug("meson i2c: timeout\n");
+				return -ETIMEDOUT;
+			}
+			udelay(1);
+		}
+		meson_i2c_reset_tokens(i2c);
+		clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
+
+		if (readl(&i2c->regs->ctrl) & REG_CTRL_ERROR) {
+			debug("meson i2c: error\n");
+			return -ENXIO;
+		}
+
+		if ((msg->flags & I2C_M_RD) && i2c->count) {
+			meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
+					   i2c->count);
+		}
+		i2c->pos += i2c->count;
+	} while (i2c->pos < msg->len);
+
+	return 0;
+}
+
+static int meson_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
+			  int nmsgs)
+{
+	struct meson_i2c *i2c = dev_get_priv(bus);
+	int i, ret = 0;
+
+	for (i = 0; i < nmsgs; i++) {
+		ret = meson_i2c_xfer_msg(i2c, msg + i, i == nmsgs - 1);
+		if (ret)
+			return -EREMOTEIO;
+	}
+
+	return 0;
+}
+
+static int meson_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
+{
+	struct meson_i2c *i2c = dev_get_priv(bus);
+	unsigned int clk_rate = MESON_I2C_CLK_RATE;
+	unsigned int div;
+
+	div = DIV_ROUND_UP(clk_rate, speed * 4);
+
+	/* clock divider has 12 bits */
+	if (div >= (1 << 12)) {
+		debug("meson i2c: requested bus frequency too low\n");
+		div = (1 << 12) - 1;
+	}
+
+	clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
+			(div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
+
+	clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIVEXT_MASK,
+			(div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
+
+	debug("meson i2c: set clk %u, src %u, div %u\n", speed, clk_rate, div);
+
+	return 0;
+}
+
+static int meson_i2c_probe(struct udevice *bus)
+{
+	struct meson_i2c *i2c = dev_get_priv(bus);
+
+	i2c->regs = dev_read_addr_ptr(bus);
+	clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
+
+	return 0;
+}
+
+static const struct dm_i2c_ops meson_i2c_ops = {
+	.xfer          = meson_i2c_xfer,
+	.set_bus_speed = meson_i2c_set_bus_speed,
+};
+
+static const struct udevice_id meson_i2c_ids[] = {
+	{ .compatible = "amlogic,meson6-i2c" },
+	{ .compatible = "amlogic,meson-gx-i2c" },
+	{ .compatible = "amlogic,meson-gxbb-i2c" },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_meson) = {
+	.name = "i2c_meson",
+	.id   = UCLASS_I2C,
+	.of_match = meson_i2c_ids,
+	.probe = meson_i2c_probe,
+	.priv_auto_alloc_size = sizeof(struct meson_i2c),
+	.ops = &meson_i2c_ops,
+};