Re: [PATCHv2 3/8] devfreq: exynos4: Add ppmu's clock control and code clean about regulator control

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Hi Chanwoo,

On 13.03.2014 09:17, Chanwoo Choi wrote:
There are not the clock controller of ppmudmc0/1. This patch control the clock
of ppmudmc0/1 which is used for monitoring memory bus utilization.

Also, this patch code clean about regulator control and free resource
when calling exit/remove function.

For example,
busfreq@106A0000 {
	compatible = "samsung,exynos4x12-busfreq";

	/* Clock for PPMUDMC0/1 */
	clocks = <&clock CLK_PPMUDMC0>, <&clock CLK_PPMUDMC1>;
	clock-names = "ppmudmc0", "ppmudmc1";

	/* Regulator for MIF/INT block */
	vdd_mif-supply = <&buck1_reg>;
	vdd_int-supply = <&buck3_reg>;
};

Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
---
  drivers/devfreq/exynos/exynos4_bus.c | 114 ++++++++++++++++++++++++++++++-----
  1 file changed, 100 insertions(+), 14 deletions(-)

diff --git a/drivers/devfreq/exynos/exynos4_bus.c b/drivers/devfreq/exynos/exynos4_bus.c
index 1a0effa..a2a3a47 100644
--- a/drivers/devfreq/exynos/exynos4_bus.c
+++ b/drivers/devfreq/exynos/exynos4_bus.c
@@ -62,6 +62,11 @@ enum exynos_ppmu_idx {
  	PPMU_END,
  };

+static const char *exynos_ppmu_clk_name[] = {
+	[PPMU_DMC0]	= "ppmudmc0",
+	[PPMU_DMC1]	= "ppmudmc1",
+};
+
  #define EX4210_LV_MAX	LV_2
  #define EX4x12_LV_MAX	LV_4
  #define EX4210_LV_NUM	(LV_2 + 1)
@@ -86,6 +91,7 @@ struct busfreq_data {
  	struct regulator *vdd_mif; /* Exynos4412/4212 only */
  	struct busfreq_opp_info curr_oppinfo;
  	struct exynos_ppmu ppmu[PPMU_END];
+	struct clk *clk_ppmu[PPMU_END];

  	struct notifier_block pm_notifier;
  	struct mutex lock;
@@ -722,8 +728,26 @@ static int exynos4_bus_get_dev_status(struct device *dev,
  static void exynos4_bus_exit(struct device *dev)
  {
  	struct busfreq_data *data = dev_get_drvdata(dev);
+	int i;
+
+	/*
+	 * Un-map memory map and disable regulator/clocks
+	 * to prevent power leakage.
+	 */
+	regulator_disable(data->vdd_int);
+	if (data->type == TYPE_BUSF_EXYNOS4x12)
+		regulator_disable(data->vdd_mif);
+
+	for (i = 0; i < PPMU_END; i++) {
+		if (data->clk_ppmu[i])

This check is invalid. Clock pointers must be checked for validity using the IS_ERR() macro, because NULL is a valid clock pointer value indicating a dummy clock.

+			clk_disable_unprepare(data->clk_ppmu[i]);
+	}

-	devfreq_unregister_opp_notifier(dev, data->devfreq);
+	for (i = 0; i < PPMU_END; i++) {
+		if (data->ppmu[i].hw_base)

Can this even happen? Is there a PPMU without registers?

+			iounmap(data->ppmu[i].hw_base);
+
+	}
  }

  static struct devfreq_dev_profile exynos4_devfreq_profile = {
@@ -987,6 +1011,7 @@ static int exynos4_busfreq_parse_dt(struct busfreq_data *data)
  {
  	struct device *dev = data->dev;
  	struct device_node *np = dev->of_node;
+	const char **clk_name = exynos_ppmu_clk_name;
  	int i, ret;

  	if (!np) {
@@ -1005,8 +1030,70 @@ static int exynos4_busfreq_parse_dt(struct busfreq_data *data)
  		}
  	}

+	/*
+	 * Get PPMU's clocks to control them. But, if PPMU's clocks
+	 * is default 'pass' state, this driver don't need control
+	 * PPMU's clock.
+	 */
+	for (i = 0; i < PPMU_END; i++) {
+		data->clk_ppmu[i] = devm_clk_get(dev, clk_name[i]);
+		if (IS_ERR_OR_NULL(data->clk_ppmu[i])) {

Again, this check is invalid. Only IS_ERR() is the correct way to check whether returned clock pointer is valid.

+			dev_warn(dev, "Cannot get %s clock\n", clk_name[i]);
+			data->clk_ppmu[i] = NULL;

This assignment is wrong. To allow further checking whether the clock was found the value returned from devm_clk_get() must be retained and then IS_ERR() used in further code.

However, I believe it should be an error if a clock is not provided. The driver must make sure that PPMU clocks are ungated before trying to access them, otherwise the system might hang.

+		}
+
+		ret = clk_prepare_enable(data->clk_ppmu[i]);

The code above allows the clock to be skipped, but this line doesn't check whether it is valid. Still, I think the clock should be always required.

+		if (ret < 0) {
+			dev_warn(dev, "Cannot enable %s clock\n", clk_name[i]);
+			data->clk_ppmu[i] = NULL;
+			goto err_clocks;
+		}
+	}
+
+	/* Get regulator to control voltage of int block */
+	data->vdd_int = devm_regulator_get(dev, "vdd_int");
+	if (IS_ERR(data->vdd_int)) {
+		dev_err(dev, "Failed to get the regulator of vdd_int\n");
+		ret = PTR_ERR(data->vdd_int);
+		goto err_clocks;
+	}
+	ret = regulator_enable(data->vdd_int);
+	if (ret < 0) {
+		dev_err(dev, "Failed to enable regulator of vdd_int\n");
+		goto err_clocks;
+	}
+
+	switch (data->type) {
+	case TYPE_BUSF_EXYNOS4210:
+		break;
+	case TYPE_BUSF_EXYNOS4x12:
+		/* Get regulator to control voltage of mif blk if Exynos4x12 */
+		data->vdd_mif = devm_regulator_get(dev, "vdd_mif");
+		if (IS_ERR(data->vdd_mif)) {
+			dev_err(dev, "Failed to get the regulator vdd_mif\n");
+			ret = PTR_ERR(data->vdd_mif);
+			goto err_regulator;
+		}
+		ret = regulator_enable(data->vdd_mif);
+		if (ret < 0) {
+			dev_err(dev, "Failed to enable regulator of vdd_mif\n");
+			goto err_regulator;
+		}
+		break;
+	default:
+		dev_err(dev, "Unknown device type : %d\n", data->type);
+		return -EINVAL;
+	};
+
  	return 0;

+err_regulator:
+	regulator_disable(data->vdd_int);
+err_clocks:
+	for (i = 0; i < PPMU_END; i++) {
+		if (data->clk_ppmu[i])

Invalid check.

Best regards,
Tomasz
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