[PATCH 5.4 008/203] i2c: bcm2835: Store pointer to bus clock

Greg Kroah-Hartman
2020-01-16T23:19:47Z

From: Stefan Wahren <wahrenst@gmx.net>

commit 3b722da6672df8392f9c43d7c7e04bddd81d7e37 upstream.

The commit bebff81fb8b9 ("i2c: bcm2835: Model Divider in CCF") introduced
a NULL pointer dereference on driver unload. It seems that we can't fetch
the bus clock via devm_clk_get in bcm2835_i2c_remove. As an alternative
approach store a pointer to the bus clock in the private driver structure.

Fixes: bebff81fb8b9 ("i2c: bcm2835: Model Divider in CCF")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/i2c/busses/i2c-bcm2835.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -58,6 +58,7 @@ struct bcm2835_i2c_dev {
struct i2c_adapter adapter;
struct completion completion;
struct i2c_msg *curr_msg;
+ struct clk *bus_clk;
int num_msgs;
u32 msg_err;
u8 *msg_buf;
@@ -404,7 +405,6 @@ static int bcm2835_i2c_probe(struct plat
struct resource *mem, *irq;
int ret;
struct i2c_adapter *adap;
- struct clk *bus_clk;
struct clk *mclk;
u32 bus_clk_rate;

@@ -427,11 +427,11 @@ static int bcm2835_i2c_probe(struct plat
return PTR_ERR(mclk);
}

- bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);
+ i2c_dev->bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);

- if (IS_ERR(bus_clk)) {
+ if (IS_ERR(i2c_dev->bus_clk)) {
dev_err(&pdev->dev, "Could not register clock\n");
- return PTR_ERR(bus_clk);
+ return PTR_ERR(i2c_dev->bus_clk);
}

ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
@@ -442,13 +442,13 @@ static int bcm2835_i2c_probe(struct plat
bus_clk_rate = 100000;
}

- ret = clk_set_rate_exclusive(bus_clk, bus_clk_rate);
+ ret = clk_set_rate_exclusive(i2c_dev->bus_clk, bus_clk_rate);
if (ret < 0) {
dev_err(&pdev->dev, "Could not set clock frequency\n");
return ret;
}

- ret = clk_prepare_enable(bus_clk);
+ ret = clk_prepare_enable(i2c_dev->bus_clk);
if (ret) {
dev_err(&pdev->dev, "Couldn't prepare clock");
return ret;
@@ -491,10 +491,9 @@ static int bcm2835_i2c_probe(struct plat
static int bcm2835_i2c_remove(struct platform_device *pdev)
{
struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
- struct clk *bus_clk = devm_clk_get(i2c_dev->dev, "div");

- clk_rate_exclusive_put(bus_clk);
- clk_disable_unprepare(bus_clk);
+ clk_rate_exclusive_put(i2c_dev->bus_clk);
+ clk_disable_unprepare(i2c_dev->bus_clk);

free_irq(i2c_dev->irq, i2c_dev);
i2c_del_adapter(&i2c_dev->adapter);