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* [PATCH] rtc: rv3028: add clkout support
@ 2019-09-27 14:15 Parthiban Nallathambi
  2019-10-11  9:17 ` Alexandre Belloni
  0 siblings, 1 reply; 3+ messages in thread
From: Parthiban Nallathambi @ 2019-09-27 14:15 UTC (permalink / raw)
  To: a.zummo, alexandre.belloni
  Cc: linux-rtc, linux-kernel, parthitce, Parthiban Nallathambi

rv3028 provides clkout (enabled by default). Add clkout
to clock framework source and control from device tree for
variable frequency with enable and disable functionality.

Signed-off-by: Parthiban Nallathambi <pn@denx.de>
---
 drivers/rtc/rtc-rv3028.c | 156 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)

diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c
index 2b316661a578..61a2ed32639f 100644
--- a/drivers/rtc/rtc-rv3028.c
+++ b/drivers/rtc/rtc-rv3028.c
@@ -8,6 +8,7 @@
  *
  */
 
+#include <linux/clk-provider.h>
 #include <linux/bcd.h>
 #include <linux/bitops.h>
 #include <linux/i2c.h>
@@ -52,6 +53,11 @@
 #define RV3028_STATUS_CLKF		BIT(6)
 #define RV3028_STATUS_EEBUSY		BIT(7)
 
+#define RV3028_CLKOUT_FD_MASK		GENMASK(2, 0)
+#define RV3028_CLKOUT_PORIE		BIT(3)
+#define RV3028_CLKOUT_CLKSY		BIT(6)
+#define RV3028_CLKOUT_CLKOE		BIT(7)
+
 #define RV3028_CTRL1_EERD		BIT(3)
 #define RV3028_CTRL1_WADA		BIT(5)
 
@@ -84,6 +90,9 @@ struct rv3028_data {
 	struct regmap *regmap;
 	struct rtc_device *rtc;
 	enum rv3028_type type;
+#ifdef CONFIG_COMMON_CLK
+	struct clk_hw clkout_hw;
+#endif
 };
 
 static u16 rv3028_trickle_resistors[] = {1000, 3000, 6000, 11000};
@@ -581,6 +590,150 @@ static int rv3028_eeprom_read(void *priv, unsigned int offset, void *val,
 	return ret;
 }
 
+#ifdef CONFIG_COMMON_CLK
+#define clkout_hw_to_rv3028(hw) container_of(hw, struct rv3028_data, clkout_hw)
+
+static int clkout_rates[] = {
+	32768,
+	8192,
+	1024,
+	64,
+	32,
+	1,
+};
+
+static unsigned long rv3028_clkout_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	int clkout, ret;
+	struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+	ret = regmap_read(rv3028->regmap, RV3028_CLKOUT, &clkout);
+	if (ret < 0)
+		return 0;
+
+	clkout &= RV3028_CLKOUT_FD_MASK;
+	return clkout_rates[clkout];
+}
+
+static long rv3028_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long *prate)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
+		if (clkout_rates[i] <= rate)
+			return clkout_rates[i];
+
+	return 0;
+}
+
+static int rv3028_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	int i, ret;
+	struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+	ret = regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(rv3028->regmap, RV3028_STATUS,
+				 RV3028_STATUS_CLKF, 0);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++) {
+		if (clkout_rates[i] == rate) {
+			ret = regmap_update_bits(rv3028->regmap,
+						 RV3028_CLKOUT,
+						 RV3028_CLKOUT_FD_MASK, i);
+			if (ret < 0)
+				return ret;
+
+			return regmap_write(rv3028->regmap, RV3028_CLKOUT,
+				RV3028_CLKOUT_CLKSY | RV3028_CLKOUT_CLKOE);
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int rv3028_clkout_prepare(struct clk_hw *hw)
+{
+	struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+	return regmap_write(rv3028->regmap, RV3028_CLKOUT,
+			    RV3028_CLKOUT_CLKSY | RV3028_CLKOUT_CLKOE);
+}
+
+static void rv3028_clkout_unprepare(struct clk_hw *hw)
+{
+	struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+	regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
+	regmap_update_bits(rv3028->regmap, RV3028_STATUS,
+			   RV3028_STATUS_CLKF, 0);
+}
+
+static int rv3028_clkout_is_prepared(struct clk_hw *hw)
+{
+	int clkout, ret;
+	struct rv3028_data *rv3028 = clkout_hw_to_rv3028(hw);
+
+	ret = regmap_read(rv3028->regmap, RV3028_CLKOUT, &clkout);
+	if (ret < 0)
+		return ret;
+
+	return !!(clkout & RV3028_CLKOUT_CLKOE);
+}
+
+static const struct clk_ops rv3028_clkout_ops = {
+	.prepare = rv3028_clkout_prepare,
+	.unprepare = rv3028_clkout_unprepare,
+	.is_prepared = rv3028_clkout_is_prepared,
+	.recalc_rate = rv3028_clkout_recalc_rate,
+	.round_rate = rv3028_clkout_round_rate,
+	.set_rate = rv3028_clkout_set_rate,
+};
+
+static int rv3028_clkout_register_clk(struct rv3028_data *rv3028,
+				      struct i2c_client *client)
+{
+	int ret;
+	struct clk *clk;
+	struct clk_init_data init;
+	struct device_node *node = client->dev.of_node;
+
+	/* disable the clkout output */
+	ret = regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(rv3028->regmap, RV3028_STATUS,
+				 RV3028_STATUS_CLKF, 0);
+	if (ret < 0)
+		return ret;
+
+	init.name = "rv3028-clkout";
+	init.ops = &rv3028_clkout_ops;
+	init.flags = 0;
+	init.parent_names = NULL;
+	init.num_parents = 0;
+	rv3028->clkout_hw.init = &init;
+
+	/* optional override of the clockname */
+	of_property_read_string(node, "clock-output-names", &init.name);
+
+	/* register the clock */
+	clk = devm_clk_register(&client->dev, &rv3028->clkout_hw);
+	if (!IS_ERR(clk))
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+
+	return 0;
+}
+#endif
+
 static struct rtc_class_ops rv3028_rtc_ops = {
 	.read_time = rv3028_get_time,
 	.set_time = rv3028_set_time,
@@ -708,6 +861,9 @@ static int rv3028_probe(struct i2c_client *client)
 
 	rv3028->rtc->max_user_freq = 1;
 
+#ifdef CONFIG_COMMON_CLK
+	rv3028_clkout_register_clk(rv3028, client);
+#endif
 	return 0;
 }
 
-- 
2.21.0


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] rtc: rv3028: add clkout support
  2019-09-27 14:15 [PATCH] rtc: rv3028: add clkout support Parthiban Nallathambi
@ 2019-10-11  9:17 ` Alexandre Belloni
  2019-10-18 10:02   ` Parthiban Nallathambi
  0 siblings, 1 reply; 3+ messages in thread
From: Alexandre Belloni @ 2019-10-11  9:17 UTC (permalink / raw)
  To: Parthiban Nallathambi; +Cc: a.zummo, linux-rtc, linux-kernel, parthitce

Hi,

thanks for the patch, minor comments below.

On 27/09/2019 16:15:05+0200, Parthiban Nallathambi wrote:
> +	ret = regmap_update_bits(rv3028->regmap, RV3028_STATUS,
> +				 RV3028_STATUS_CLKF, 0);
> +	if (ret < 0)
> +		return ret;
> +

This is already done earlier and this will not be enabled again unless
CLKIE is set which should not happen. So I don't think it is necessary
to do it once again here.

> +	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++) {
> +		if (clkout_rates[i] == rate) {
> +			ret = regmap_update_bits(rv3028->regmap,
> +						 RV3028_CLKOUT,
> +						 RV3028_CLKOUT_FD_MASK, i);
> +			if (ret < 0)
> +				return ret;
> +
> +			return regmap_write(rv3028->regmap, RV3028_CLKOUT,
> +				RV3028_CLKOUT_CLKSY | RV3028_CLKOUT_CLKOE);
> +		}
> +	}
> +
> +	return -EINVAL;
> +}


> +static int rv3028_clkout_register_clk(struct rv3028_data *rv3028,
> +				      struct i2c_client *client)
> +{
> +	int ret;
> +	struct clk *clk;
> +	struct clk_init_data init;
> +	struct device_node *node = client->dev.of_node;
> +
> +	/* disable the clkout output */
> +	ret = regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
> +	if (ret < 0)
> +		return ret;
> +

This is not what the user would expect and could introduce a glitch in 
the clock output every time the platform is booted. If there are no 
users of the clock, then you should probably let the core disable it 
once the boot has ended.


-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] rtc: rv3028: add clkout support
  2019-10-11  9:17 ` Alexandre Belloni
@ 2019-10-18 10:02   ` Parthiban Nallathambi
  0 siblings, 0 replies; 3+ messages in thread
From: Parthiban Nallathambi @ 2019-10-18 10:02 UTC (permalink / raw)
  To: Alexandre Belloni; +Cc: pn, a.zummo, linux-rtc, linux-kernel, parthitce

Hi,

Thanks for the comments. Will send v2 with changes.

On 10/11/19 11:17 AM, Alexandre Belloni wrote:
> Hi,
> 
> thanks for the patch, minor comments below.
> 
> On 27/09/2019 16:15:05+0200, Parthiban Nallathambi wrote:
>> +	ret = regmap_update_bits(rv3028->regmap, RV3028_STATUS,
>> +				 RV3028_STATUS_CLKF, 0);
>> +	if (ret < 0)
>> +		return ret;
>> +
> 
> This is already done earlier and this will not be enabled again unless
> CLKIE is set which should not happen. So I don't think it is necessary
> to do it once again here.

Agree, removed in v2.

> 
>> +	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++) {
>> +		if (clkout_rates[i] == rate) {
>> +			ret = regmap_update_bits(rv3028->regmap,
>> +						 RV3028_CLKOUT,
>> +						 RV3028_CLKOUT_FD_MASK, i);
>> +			if (ret < 0)
>> +				return ret;
>> +
>> +			return regmap_write(rv3028->regmap, RV3028_CLKOUT,
>> +				RV3028_CLKOUT_CLKSY | RV3028_CLKOUT_CLKOE);
>> +		}
>> +	}
>> +
>> +	return -EINVAL;
>> +}
> 
> 
>> +static int rv3028_clkout_register_clk(struct rv3028_data *rv3028,
>> +				      struct i2c_client *client)
>> +{
>> +	int ret;
>> +	struct clk *clk;
>> +	struct clk_init_data init;
>> +	struct device_node *node = client->dev.of_node;
>> +
>> +	/* disable the clkout output */
>> +	ret = regmap_write(rv3028->regmap, RV3028_CLKOUT, 0x0);
>> +	if (ret < 0)
>> +		return ret;
>> +
> 
> This is not what the user would expect and could introduce a glitch in
> the clock output every time the platform is booted. If there are no
> users of the clock, then you should probably let the core disable it
> once the boot has ended.

Thanks, removed in v2.

> 
> 

-- 
Thanks,
Parthiban N

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-22 Fax: (+49)-8142-66989-80 Email: pn@denx.de

^ permalink raw reply	[flat|nested] 3+ messages in thread

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2019-09-27 14:15 [PATCH] rtc: rv3028: add clkout support Parthiban Nallathambi
2019-10-11  9:17 ` Alexandre Belloni
2019-10-18 10:02   ` Parthiban Nallathambi

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