[PATCH 10/13] i2c: nomadik: support Mobileye EyeQ5 I2C controller

["Théo Lebrun" <theo.lebrun@bootlin.com>]

Add compatible for the integration of the same DB8500 IP block into the
Mobileye EyeQ5 platform. Two quirks are present:

 - The memory bus only supports 32-bit accesses. One writeb() is done to
   fill the Tx FIFO which we replace with a writel().

 - A register must be configured for the I2C speed mode; it is located
   in a shared register region called OLB. We access that memory region
   using a syscon & regmap that gets passed as a phandle (mobileye,olb).

   A two-bit enum per controller is written into the register; that
   requires us to know the global index of the I2C
   controller (mobileye,id).

We add #include <linux/mfd/syscon.h> and <linux/regmap.h> and sort
headers.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
---
 drivers/i2c/busses/i2c-nomadik.c | 79 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-nomadik.c b/drivers/i2c/busses/i2c-nomadik.c
index 23e12c570457..eb076419dfa8 100644
--- a/drivers/i2c/busses/i2c-nomadik.c
+++ b/drivers/i2c/busses/i2c-nomadik.c
@@ -6,22 +6,30 @@
  * I2C master mode controller driver, used in Nomadik 8815
  * and Ux500 platforms.
  *
+ * The Mobileye EyeQ5 platform is also supported; it uses
+ * the same Ux500/DB8500 IP block with two quirks:
+ *  - The memory bus only supports 32-bit accesses.
+ *  - A register must be configured for the I2C speed mode;
+ *    it is located in a shared register region called OLB.
+ *
  * Author: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
  * Author: Sachin Verma <sachin.verma@st.com>
  */
+#include <linux/amba/bus.h>
 #include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
 #include <linux/init.h>
-#include <linux/module.h>
-#include <linux/amba/bus.h>
-#include <linux/slab.h>
 #include <linux/interrupt.h>
-#include <linux/i2c.h>
-#include <linux/err.h>
-#include <linux/clk.h>
 #include <linux/io.h>
-#include <linux/pm_runtime.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
 #include <linux/of.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
 
 #define DRIVER_NAME "nmk-i2c"
 
@@ -110,6 +118,10 @@ enum i2c_freq_mode {
 	I2C_FREQ_MODE_FAST_PLUS,	/* up to 1 Mb/s */
 };
 
+/* Mobileye EyeQ5 offset into a shared register region (called OLB) */
+#define NMK_I2C_EYEQ5_OLB_IOCR2			0x0B8
+#define NMK_I2C_EYEQ5_OLB_IOCR2_SHIFT(id)	(4 + 2 * (id))
+
 /**
  * struct i2c_vendor_data - per-vendor variations
  * @has_mtdws: variant has the MTDWS bit
@@ -168,6 +180,7 @@ struct i2c_nmk_client {
  * @xfer_wq: xfer done wait queue.
  * @xfer_done: xfer done boolean.
  * @result: controller propogated result.
+ * @has_32b_bus: controller is on a bus that only supports 32-bit accesses.
  */
 struct nmk_i2c_dev {
 	struct i2c_vendor_data		*vendor;
@@ -186,6 +199,7 @@ struct nmk_i2c_dev {
 	struct wait_queue_head		xfer_wq;
 	bool				xfer_done;
 	int				result;
+	bool				has_32b_bus;
 };
 
 /* controller's abort causes */
@@ -514,7 +528,10 @@ static void fill_tx_fifo(struct nmk_i2c_dev *priv, int no_bytes)
 			(priv->cli.count != 0);
 			count--) {
 		/* write to the Tx FIFO */
-		writeb(*priv->cli.buffer, priv->virtbase + I2C_TFR);
+		if (priv->has_32b_bus)
+			writel(*priv->cli.buffer, priv->virtbase + I2C_TFR);
+		else
+			writeb(*priv->cli.buffer, priv->virtbase + I2C_TFR);
 		priv->cli.buffer++;
 		priv->cli.count--;
 		priv->cli.xfer_bytes++;
@@ -985,6 +1002,43 @@ static void nmk_i2c_of_probe(struct device_node *np,
 		priv->timeout_usecs = 200 * USEC_PER_MSEC;
 }
 
+static int nmk_i2c_eyeq5_probe(struct nmk_i2c_dev *priv)
+{
+	struct device *dev = &priv->adev->dev;
+	struct device_node *np = dev->of_node;
+	unsigned int shift, speed_mode;
+	struct regmap *olb;
+	int ret;
+	u32 id;
+
+	priv->has_32b_bus = true;
+
+	olb = syscon_regmap_lookup_by_phandle(np, "mobileye,olb");
+	if (IS_ERR_OR_NULL(olb)) {
+		if (!olb)
+			olb = ERR_PTR(-ENOENT);
+		return dev_err_probe(dev, PTR_ERR(olb),
+				     "failed OLB lookup: %lu\n", PTR_ERR(olb));
+	}
+
+	ret = of_property_read_u32(np, "mobileye,id", &id);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed ID lookup: %d\n", ret);
+
+	if (priv->clk_freq <= 400000)
+		speed_mode = 0b00;
+	else if (priv->clk_freq <= 1000000)
+		speed_mode = 0b01;
+	else
+		speed_mode = 0b10;
+
+	shift = NMK_I2C_EYEQ5_OLB_IOCR2_SHIFT(id);
+	regmap_update_bits(olb, NMK_I2C_EYEQ5_OLB_IOCR2,
+			   0b11 << shift, speed_mode << shift);
+
+	return 0;
+}
+
 static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
 {
 	int ret = 0;
@@ -1001,8 +1055,17 @@ static int nmk_i2c_probe(struct amba_device *adev, const struct amba_id *id)
 
 	priv->vendor = vendor;
 	priv->adev = adev;
+	priv->has_32b_bus = false;
 	nmk_i2c_of_probe(np, priv);
 
+	if (of_device_is_compatible(np, "mobileye,eyeq5-i2c")) {
+		ret = nmk_i2c_eyeq5_probe(priv);
+		if (ret) {
+			dev_info(dev, "%s: %d: %d\n", __func__, __LINE__, ret);
+			return ret;
+		}
+	}
+
 	if (priv->tft > max_fifo_threshold) {
 		dev_warn(dev, "requested TX FIFO threshold %u, adjusted down to %u\n",
 			 priv->tft, max_fifo_threshold);

-- 
2.43.1