make the MPC I2C driver get, prepare and enable the peripheral clock
during probe ('per' for access to the peripheral's registers); 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 enable errors for
specified clocks are considered fatal
Signed-off-by: Gerhard Sittig <gsi@xxxxxxx>
---
drivers/i2c/busses/i2c-mpc.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 7607dc0..4b00dd0 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -21,6 +21,7 @@
#include <linux/of_i2c.h>
#include <linux/slab.h>
+#include <linux/clk.h>
#include <linux/io.h>
#include <linux/fsl_devices.h>
#include <linux/i2c.h>
@@ -67,6 +68,7 @@ struct mpc_i2c {
#ifdef CONFIG_PM
u8 fdr, dfsrr;
#endif
+ struct clk *clk_per;
};
struct mpc_i2c_divider {
@@ -623,6 +625,8 @@ static int fsl_i2c_probe(struct platform_device *op)
u32 clock = MPC_I2C_CLOCK_LEGACY;
int result = 0;
int plen;
+ struct clk *clk;
+ int err;
match = of_match_device(mpc_i2c_of_match, &op->dev);
if (!match)
@@ -653,6 +657,21 @@ 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, "per");
+ 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 {
@@ -696,6 +715,8 @@ 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);
@@ -711,6 +732,9 @@ 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);
--
1.7.10.4
--
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