i2c: mpc: cleanup clock API use

make the MPC I2C driver get, prepare and enable the gated clock item for
register access during probe; disable and unprepare the clock upon
remove(), put is done by the devm approach; hold a reference to the
clock over the period of use

clock lookup is non-fatal in this implementation as not all platforms
may provide clock specs in their device tree, but failure to enable a
clock when specified is considered fatal

Signed-off-by: Gerhard Sittig <gsi@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index f4060939e959..b80c76888cab 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -20,6 +20,7 @@
 #include <linux/of_platform.h>
 #include <linux/slab.h>
 
+#include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/fsl_devices.h>
 #include <linux/i2c.h>
@@ -66,6 +67,7 @@ struct mpc_i2c {
 #ifdef CONFIG_PM_SLEEP
         u8 fdr, dfsrr;
 #endif
+        struct clk *clk_per;
 };
 
 struct mpc_i2c_divider {
@@ -622,6 +624,8 @@ static int fsl_i2c_probe(struct platform_device *op)
         int result = 0;
         int plen;
         struct resource res;
+        struct clk *clk;
+        int err;
 
         match = of_match_device(mpc_i2c_of_match, &op->dev);
         if (!match)
@@ -652,6 +656,21 @@ static int fsl_i2c_probe(struct platform_device *op)
                 }
         }
 
+        /*
+         * enable clock for the I2C peripheral (non fatal),
+         * keep a reference upon successful allocation
+         */
+        clk = devm_clk_get(&op->dev, NULL);
+        if (!IS_ERR(clk)) {
+                err = clk_prepare_enable(clk);
+                if (err) {
+                        dev_err(&op->dev, "failed to enable clock\n");
+                        goto fail_request;
+                } else {
+                        i2c->clk_per = clk;
+                }
+        }
+
         if (of_get_property(op->dev.of_node, "fsl,preserve-clocking", NULL)) {
                 clock = MPC_I2C_CLOCK_PRESERVE;
         } else {
@@ -697,6 +716,8 @@ static int fsl_i2c_probe(struct platform_device *op)
         return result;
 
  fail_add:
+        if (i2c->clk_per)
+                clk_disable_unprepare(i2c->clk_per);
         free_irq(i2c->irq, i2c);
  fail_request:
         irq_dispose_mapping(i2c->irq);
@@ -712,6 +733,9 @@ static int fsl_i2c_remove(struct platform_device *op)
 
         i2c_del_adapter(&i2c->adap);
 
+        if (i2c->clk_per)
+                clk_disable_unprepare(i2c->clk_per);
+
         if (i2c->irq)
                 free_irq(i2c->irq, i2c);