[PATCH] i2c: bcm2835: Ensure clock exists when probing

[PATCH] i2c: bcm2835: Ensure clock exists when probing

[Annaliese McDermond]

Probe function fails to recognize that upstram clock actually
doesn't yet exist because clock driver has not been initialized.
Actually try to go get the clock and test for its existence
before trying to set up a downstream clock based upon it.

This fixes a bug that causes the i2c driver not to work with
monolithic kernels.

Signed-off-by: Annaliese McDermond <nh6z@nh6z.net>
---
 drivers/i2c/busses/i2c-bcm2835.c | 42 +++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index 5b556274cdb6..67752f7b0371 100644
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -154,15 +154,18 @@ static const struct clk_ops clk_bcm2835_i2c_ops = {
 };
 
 static struct clk *bcm2835_i2c_register_div(struct device *dev,
-					const char *mclk_name,
+					struct clk *mclk,
 					struct bcm2835_i2c_dev *i2c_dev)
 {
 	struct clk_init_data init;
 	struct clk_bcm2835_i2c *priv;
 	char name[32];
+	const char *mclk_name;
 
 	snprintf(name, sizeof(name), "%s_div", dev_name(dev));
 
+	mclk_name = __clk_get_name(mclk);
+
 	init.ops = &clk_bcm2835_i2c_ops;
 	init.name = name;
 	init.parent_names = (const char* []) { mclk_name };
@@ -400,8 +403,8 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 	struct resource *mem, *irq;
 	int ret;
 	struct i2c_adapter *adap;
-	const char *mclk_name;
 	struct clk *bus_clk;
+	struct clk *mclk;
 	u32 bus_clk_rate;
 
 	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
@@ -416,23 +419,14 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 	if (IS_ERR(i2c_dev->regs))
 		return PTR_ERR(i2c_dev->regs);
 
-	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-	if (!irq) {
-		dev_err(&pdev->dev, "No IRQ resource\n");
-		return -ENODEV;
-	}
-	i2c_dev->irq = irq->start;
-
-	ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
-			  dev_name(&pdev->dev), i2c_dev);
-	if (ret) {
-		dev_err(&pdev->dev, "Could not request IRQ\n");
-		return -ENODEV;
+	mclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(mclk)) {
+		if (PTR_ERR(mclk) != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "Could not get clock\n");
+		return PTR_ERR(mclk);
 	}
 
-	mclk_name = of_clk_get_parent_name(pdev->dev.of_node, 0);
-
-	bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk_name, i2c_dev);
+	bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);
 
 	if (IS_ERR(bus_clk)) {
 		dev_err(&pdev->dev, "Could not register clock\n");
@@ -459,6 +453,20 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!irq) {
+		dev_err(&pdev->dev, "No IRQ resource\n");
+		return -ENODEV;
+	}
+	i2c_dev->irq = irq->start;
+
+	ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
+			  dev_name(&pdev->dev), i2c_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not request IRQ\n");
+		return -ENODEV;
+	}
+
 	adap = &i2c_dev->adapter;
 	i2c_set_adapdata(adap, i2c_dev);
 	adap->owner = THIS_MODULE;
-- 
2.19.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] i2c: bcm2835: Ensure clock exists when probing

[Stefan Wahren]

Hi Annaliese,

Am 21.06.19 um 06:26 schrieb Annaliese McDermond:
> Probe function fails to recognize that upstram clock actually
s/upstram/upstream/
> doesn't yet exist because clock driver has not been initialized.
> Actually try to go get the clock and test for its existence
> before trying to set up a downstream clock based upon it.
>
> This fixes a bug that causes the i2c driver not to work with
> monolithic kernels.

I suggest to split the change into 2 patches (first reorder probing,
second clock) with a small cover letter. This makes the changes more
obvious and easier to review. Please also add a Fixes tags to see the
related commit.

Btw please use my new maintainer mail address

Thanks Stefan



_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel