[2/3] i2c: xlp9xx: Get clock frequency with clk API

Message ID 1506523943-8632-3-git-send-email-kamlakant.patel@cavium.com
State Superseded
Headers show
Series
  • i2c-xlp9xx: update i2c driver to handle I2C_M_RECV_LEN flag
Related show

Commit Message

Kamlakant Patel Sept. 27, 2017, 2:52 p.m.
From: Jayachandran C <jnair@caviumnetworks.com>

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@caviumnetworks.com>
Signed-off-by: Kamlakant Patel <kamlakant.patel@cavium.com>
---
 drivers/i2c/busses/i2c-xlp9xx.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

Comments

Mika Westerberg Sept. 28, 2017, 8:49 a.m. | #1
On Wed, Sep 27, 2017 at 08:22:22PM +0530, Kamlakant Patel wrote:
> From: Jayachandran C <jnair@caviumnetworks.com>
> 
> 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@caviumnetworks.com>
> Signed-off-by: Kamlakant Patel <kamlakant.patel@cavium.com>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Patch

diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index 6b106e9..f0bef2d 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;