Re: [PATCH v3] rtc: pcf8563: add CLKOUT to common clock framework

[Alexandre Belloni]

Hi,

You were too fast for me, I commented on v2 ;)

On 16/10/2015 at 12:39:01 +0200, Heiko Schocher wrote :
> Add the clkout output clk to the common clock framework.
> Disable the CLKOUT of the RTC after power-up.
> After power-up/reset of the RTC, CLKOUT is enabled by default,
> with CLKOUT enabled the RTC chip has 2-3 times higher power
> consumption.
> 
> Signed-off-by: Heiko Schocher <hs@xxxxxxx>
> ---
> 
> Changes in v3:
> - use CONFIG_COMMON_CLK for common clk framework
>   changes
> 
> Changes in v2:
> - add comments from Alexandre Belloni
>   - remove the DT property, instead
>     register for the CLKOUT a clk in the common
>     clk framework. The clk is disabled by default.
> 
>  Documentation/devicetree/bindings/rtc/pcf8563.txt |  28 ++++
>  drivers/rtc/rtc-pcf8563.c                         | 170 +++++++++++++++++++++-
>  2 files changed, 197 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/pcf8563.txt
> 
> diff --git a/Documentation/devicetree/bindings/rtc/pcf8563.txt b/Documentation/devicetree/bindings/rtc/pcf8563.txt
> new file mode 100644
> index 0000000..cdb81ef
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/pcf8563.txt
> @@ -0,0 +1,28 @@
> +* Philips PCF8563/Epson RTC8564 Real Time Clock
> +
> +Philips PCF8563/Epson RTC8564 Real Time Clock
> +
> +Required properties:
> +see: Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +
> +Optional property:
> +- #clock-cells: Should be 1.
> +- clocks: Reference to the clock entry.
> +- clock-output-names:
> +  overwrite the default clock name "pcf8563-clkout"
> +
> +Example:
> +
> +rtcclk: rtcclk {
> +	compatible = "fixed-clock";
> +	#clock-cells = <1>;
> +	clock-frequency = <1>;
> +	clock-output-names = "rtcclk";
> +};
> +
> +pcf8563@51 {
> +	compatible = "nxp,pcf8563";
> +	reg = <0x51>;
> +	#clock-cells = <1>;
> +	clocks = <&rtcclk 0>;
> +};
> diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
> index e569243..9db3c1f 100644
> --- a/drivers/rtc/rtc-pcf8563.c
> +++ b/drivers/rtc/rtc-pcf8563.c
> @@ -14,6 +14,7 @@
>   * published by the Free Software Foundation.
>   */
>  
> +#include <linux/clk-provider.h>
>  #include <linux/i2c.h>
>  #include <linux/bcd.h>
>  #include <linux/rtc.h>
> @@ -40,7 +41,14 @@
>  
>  #define PCF8563_REG_AMN		0x09 /* alarm */
>  
> -#define PCF8563_REG_CLKO	0x0D /* clock out */
> +#define PCF8563_REG_CLKO		0x0D /* clock out */
> +#define PCF8563_REG_CLKO_FE		0x80 /* clock out enabled */
> +#define PCF8563_REG_CLKO_F_MASK		0x03 /* frequenc mask */
> +#define PCF8563_REG_CLKO_F_32768HZ	0x00
> +#define PCF8563_REG_CLKO_F_1024HZ	0x01
> +#define PCF8563_REG_CLKO_F_32HZ		0x02
> +#define PCF8563_REG_CLKO_F_1HZ		0x03
> +
>  #define PCF8563_REG_TMRC	0x0E /* timer control */
>  #define PCF8563_TMRC_ENABLE	BIT(7)
>  #define PCF8563_TMRC_4096	0
> @@ -76,6 +84,9 @@ struct pcf8563 {
>  	int voltage_low; /* incicates if a low_voltage was detected */
>  
>  	struct i2c_client *client;
> +#ifdef CONFIG_COMMON_CLK
> +	struct clk_hw		clkout_hw;
> +#endif
>  };
>  
>  static int pcf8563_read_block_data(struct i2c_client *client, unsigned char reg,
> @@ -390,6 +401,158 @@ static int pcf8563_irq_enable(struct device *dev, unsigned int enabled)
>  	return pcf8563_set_alarm_mode(to_i2c_client(dev), !!enabled);
>  }
>  
> +#ifdef CONFIG_COMMON_CLK
> +/*
> + * Handling of the clkout
> + */
> +
> +#define clkout_hw_to_pcf8563(_hw) container_of(_hw, struct pcf8563, clkout_hw)
> +
> +static int clkout_rates[] = {
> +	32768,
> +	1024,
> +	32,
> +	1,
> +};
> +
> +static unsigned long pcf8563_clkout_recalc_rate(struct clk_hw *hw,
> +						unsigned long parent_rate)
> +{
> +	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
> +	struct i2c_client *client = pcf8563->client;
> +	unsigned char buf;
> +	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
> +
> +	if (ret < 0)
> +		return 0;
> +
> +	buf &= PCF8563_REG_CLKO_F_MASK;
> +	return clkout_rates[ret];
> +}
> +
> +static long pcf8563_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 pcf8563_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
> +				   unsigned long parent_rate)
> +{
> +	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
> +	struct i2c_client *client = pcf8563->client;
> +	unsigned char buf;
> +	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
> +	int i;
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(clkout_rates); i++)
> +		if (clkout_rates[i] == rate) {
> +			buf &= ~PCF8563_REG_CLKO_F_MASK;
> +			buf |= i;
> +			ret = pcf8563_write_block_data(client,
> +						       PCF8563_REG_CLKO, 1,
> +						       &buf);
> +			return ret;
> +		}
> +
> +	return -EINVAL;
> +}
> +
> +static int pcf8563_clkout_control(struct clk_hw *hw, bool enable)
> +{
> +	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
> +	struct i2c_client *client = pcf8563->client;
> +	unsigned char buf;
> +	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	if (enable)
> +		buf |= PCF8563_REG_CLKO_FE;
> +	else
> +		buf &= ~PCF8563_REG_CLKO_FE;
> +
> +	ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
> +	return ret;
> +}
> +
> +static int pcf8563_clkout_prepare(struct clk_hw *hw)
> +{
> +	return pcf8563_clkout_control(hw, 1);
> +}
> +
> +static void pcf8563_clkout_unprepare(struct clk_hw *hw)
> +{
> +	pcf8563_clkout_control(hw, 0);
> +}
> +
> +static int pcf8563_clkout_is_prepared(struct clk_hw *hw)
> +{
> +	struct pcf8563 *pcf8563 = clkout_hw_to_pcf8563(hw);
> +	struct i2c_client *client = pcf8563->client;
> +	unsigned char buf;
> +	int ret = pcf8563_read_block_data(client, PCF8563_REG_CLKO, 1, &buf);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return !!(buf & PCF8563_REG_CLKO_FE);
> +}
> +
> +static const struct clk_ops pcf8563_clkout_ops = {
> +	.prepare = pcf8563_clkout_prepare,
> +	.unprepare = pcf8563_clkout_unprepare,
> +	.is_prepared = pcf8563_clkout_is_prepared,
> +	.recalc_rate = pcf8563_clkout_recalc_rate,
> +	.round_rate = pcf8563_clkout_round_rate,
> +	.set_rate = pcf8563_clkout_set_rate,
> +};
> +
> +static struct clk *pcf8563_clkout_register_clk(struct pcf8563 *pcf8563)
> +{
> +	struct i2c_client *client = pcf8563->client;
> +	struct device_node *node = client->dev.of_node;
> +	struct clk *clk;
> +	struct clk_init_data init;
> +	int ret;
> +	unsigned char buf;
> +
> +	/* disable the clkout output */
> +	buf = 0;
> +	ret = pcf8563_write_block_data(client, PCF8563_REG_CLKO, 1, &buf);
> +	if (ret < 0)
> +		return ERR_PTR(ret);
> +
> +	init.name = "pcf8563-clkout";
> +	init.ops = &pcf8563_clkout_ops;
> +	init.flags = CLK_IS_ROOT;
> +	init.parent_names = NULL;
> +	init.num_parents = 0;
> +	pcf8563->clkout_hw.init = &init;
> +
> +	/* optional override of the clockname */
> +	of_property_read_string(node, "clock-output-names", &init.name);
> +
> +	/* register the clock */
> +	clk = clk_register(&client->dev, &pcf8563->clkout_hw);
> +
> +	if (!IS_ERR(clk))
> +		of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +
> +	return clk;
> +}
> +#endif
> +
>  static const struct rtc_class_ops pcf8563_rtc_ops = {
>  	.ioctl		= pcf8563_rtc_ioctl,
>  	.read_time	= pcf8563_rtc_read_time,
> @@ -459,6 +622,11 @@ static int pcf8563_probe(struct i2c_client *client,
>  
>  	}
>  
> +#ifdef CONFIG_COMMON_CLK
> +	/* register clk in common clk framework */
> +	pcf8563_clkout_register_clk(pcf8563);
> +#endif
> +
>  	/* the pcf8563 alarm only supports a minute accuracy */
>  	pcf8563->rtc->uie_unsupported = 1;
>  
> -- 
> 2.1.0
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/