openwrt/target/linux/brcm2708/patches-4.19/950-0696-i2c-bcm2835-Ensure-clock-exists-when-probing.patch

From 1a5122f1756ef4fc5779324ad26b6a04142166b5 Mon Sep 17 00:00:00 2001
From: Annaliese McDermond <nh6z@nh6z.net>
Date: Fri, 21 Jun 2019 03:52:50 -0700
Subject: [PATCH 696/806] i2c: bcm2835: Ensure clock exists when probing

Commit 9de93b04df16b055824e3f1f13fedb90fbcf2e4f upstream.

Probe function fails to recognize that upstream 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.

Fixes: bebff81fb8b9 ("i2c: bcm2835: Model Divider in CCF")
Signed-off-by: Annaliese McDermond <nh6z@nh6z.net>
Acked-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
---
 drivers/i2c/busses/i2c-bcm2835.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -244,15 +244,18 @@ static const struct clk_ops clk_bcm2835_
 };
 
 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 };
@@ -505,8 +508,8 @@ static int bcm2835_i2c_probe(struct plat
 	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);
@@ -521,9 +524,14 @@ static int bcm2835_i2c_probe(struct plat
 	if (IS_ERR(i2c_dev->regs))
 		return PTR_ERR(i2c_dev->regs);
 
-	mclk_name = of_clk_get_parent_name(pdev->dev.of_node, 0);
+	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);
+	}
 
-	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");