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Date: Fri, 16 Oct 2015 12:56:05 +0200
From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To: Heiko Schocher <hs@...x.de>
Cc: linux-kernel@...r.kernel.org, Georg.Soffel@...ch-si.com,
rtc-linux@...glegroups.com,
Alessandro Zummo <a.zummo@...ertech.it>,
devicetree@...r.kernel.org
Subject: Re: [PATCH v3] rtc: pcf8563: add CLKOUT to common clock framework
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@...x.de>
> ---
>
> 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
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