[PATCH 2/3][Bionic][SRU Artful] i2c: xlp9xx: Get clock frequency with clk API

[dann frazier]

From: Jayachandran C <jnair at caviumnetworks.com>

BugLink: https://bugs.launchpad.net/bugs/1738073

Get the input clock frequency to the controller from the linux clk
API, if it is available. This allows us to pass in the block input
frequency either from ACPI (using APD) or from device tree.

The old hardcoded frequency is used as default for backwards compatibility.

Signed-off-by: Jayachandran C <jnair at caviumnetworks.com>
Signed-off-by: Kamlakant Patel <kamlakant.patel at cavium.com>
Reviewed-by: Mika Westerberg <mika.westerberg at linux.intel.com>
Signed-off-by: Wolfram Sang <wsa at the-dreams.de>
(cherry picked from commit c347b8fc22b21899154cc153a4951aaf226b4e1a)
Signed-off-by: dann frazier <dann.frazier at canonical.com>
---
 drivers/i2c/busses/i2c-xlp9xx.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index 6b106e94bc09..f0bef2d5306c 100644
--- a/drivers/i2c/busses/i2c-xlp9xx.c
+++ b/drivers/i2c/busses/i2c-xlp9xx.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
@@ -84,6 +85,7 @@ struct xlp9xx_i2c_dev {
 	u32 __iomem *base;
 	u32 msg_buf_remaining;
 	u32 msg_len;
+	u32 ip_clk_hz;
 	u32 clk_hz;
 	u32 msg_err;
 	u8 *msg_buf;
@@ -213,7 +215,7 @@ static int xlp9xx_i2c_init(struct xlp9xx_i2c_dev *priv)
 	 * The controller uses 5 * SCL clock internally.
 	 * So prescale value should be divided by 5.
 	 */
-	prescale = DIV_ROUND_UP(XLP9XX_I2C_IP_CLK_FREQ, priv->clk_hz);
+	prescale = DIV_ROUND_UP(priv->ip_clk_hz, priv->clk_hz);
 	prescale = ((prescale - 8) / 5) - 1;
 	xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_CTRL, XLP9XX_I2C_CTRL_RST);
 	xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_CTRL, XLP9XX_I2C_CTRL_EN |
@@ -342,9 +344,19 @@ static const struct i2c_algorithm xlp9xx_i2c_algo = {
 static int xlp9xx_i2c_get_frequency(struct platform_device *pdev,
 				    struct xlp9xx_i2c_dev *priv)
 {
+	struct clk *clk;
 	u32 freq;
 	int err;
 
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		priv->ip_clk_hz = XLP9XX_I2C_IP_CLK_FREQ;
+		dev_dbg(&pdev->dev, "using default input frequency %u\n",
+			priv->ip_clk_hz);
+	} else {
+		priv->ip_clk_hz = clk_get_rate(clk);
+	}
+
 	err = device_property_read_u32(&pdev->dev, "clock-frequency", &freq);
 	if (err) {
 		freq = XLP9XX_I2C_DEFAULT_FREQ;
-- 
2.15.1