Re: [PATCH v5 4/7] rtc: ac100: Add clk output support

From: Lee Jones
Date: Mon Aug 08 2016 - 07:55:31 EST

On Fri, 08 Jul 2016, Alexandre Belloni wrote:

> On 08/07/2016 at 22:33:39 +0800, Chen-Yu Tsai wrote :
> > The AC100's RTC side has 3 clock outputs on external pins, which can
> > provide a clock signal to the SoC or other modules, such as WiFi or
> > GSM modules.
> >
> > Support this with a custom clk driver integrated with the rtc driver.
> >
> > Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
>
> > ---
> > Changes since v4: none
> >
> > Changes since v3:
> >
> > - Renamed clk32k prefixes to clkout, except for the internal 32k clk
> > - Changed default clk output names to "ac100-cko{1,2,3}-rtc"
> > - Moved 4M ADDA clk to codec side
> >
> > Changes since v2: none
> > Changes since v1: none
> >
> > ---
> > drivers/rtc/rtc-ac100.c | 302 ++++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 302 insertions(+)

Applied, thanks.

> > diff --git a/drivers/rtc/rtc-ac100.c b/drivers/rtc/rtc-ac100.c
> > index 5a9ca89d04c7..70b4fd0f6122 100644
> > --- a/drivers/rtc/rtc-ac100.c
> > +++ b/drivers/rtc/rtc-ac100.c
> > @@ -16,6 +16,7 @@
> > */
> >
> > #include <linux/bcd.h>
> > +#include <linux/clk-provider.h>
> > #include <linux/device.h>
> > #include <linux/interrupt.h>
> > #include <linux/kernel.h>
> > @@ -31,6 +32,15 @@
> > /* Control register */
> > #define AC100_RTC_CTRL_24HOUR BIT(0)
> >
> > +/* Clock output register bits */
> > +#define AC100_CLKOUT_PRE_DIV_SHIFT 5
> > +#define AC100_CLKOUT_PRE_DIV_WIDTH 3
> > +#define AC100_CLKOUT_MUX_SHIFT 4
> > +#define AC100_CLKOUT_MUX_WIDTH 1
> > +#define AC100_CLKOUT_DIV_SHIFT 1
> > +#define AC100_CLKOUT_DIV_WIDTH 3
> > +#define AC100_CLKOUT_EN BIT(0)
> > +
> > /* RTC */
> > #define AC100_RTC_SEC_MASK GENMASK(6, 0)
> > #define AC100_RTC_MIN_MASK GENMASK(6, 0)
> > @@ -67,14 +77,292 @@
> > #define AC100_YEAR_MAX 2069
> > #define AC100_YEAR_OFF (AC100_YEAR_MIN - 1900)
> >
> > +struct ac100_clkout {
> > + struct clk_hw hw;
> > + struct regmap *regmap;
> > + u8 offset;
> > +};
> > +
> > +#define to_ac100_clkout(_hw) container_of(_hw, struct ac100_clkout, hw)
> > +
> > +#define AC100_RTC_32K_NAME "ac100-rtc-32k"
> > +#define AC100_RTC_32K_RATE 32768
> > +#define AC100_CLKOUT_NUM 3
> > +
> > +static const char * const ac100_clkout_names[AC100_CLKOUT_NUM] = {
> > + "ac100-cko1-rtc",
> > + "ac100-cko2-rtc",
> > + "ac100-cko3-rtc",
> > +};
> > +
> > struct ac100_rtc_dev {
> > struct rtc_device *rtc;
> > struct device *dev;
> > struct regmap *regmap;
> > int irq;
> > unsigned long alarm;
> > +
> > + struct clk_hw *rtc_32k_clk;
> > + struct ac100_clkout clks[AC100_CLKOUT_NUM];
> > + struct clk_hw_onecell_data *clk_data;
> > };
> >
> > +/**
> > + * Clock controls for 3 clock output pins
> > + */
> > +
> > +static const struct clk_div_table ac100_clkout_prediv[] = {
> > + { .val = 0, .div = 1 },
> > + { .val = 1, .div = 2 },
> > + { .val = 2, .div = 4 },
> > + { .val = 3, .div = 8 },
> > + { .val = 4, .div = 16 },
> > + { .val = 5, .div = 32 },
> > + { .val = 6, .div = 64 },
> > + { .val = 7, .div = 122 },
> > + { },
> > +};
> > +
> > +/* Abuse the fact that one parent is 32768 Hz, and the other is 4 MHz */
> > +static unsigned long ac100_clkout_recalc_rate(struct clk_hw *hw,
> > + unsigned long prate)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > + unsigned int reg, div;
> > +
> > + regmap_read(clk->regmap, clk->offset, &reg);
> > +
> > + /* Handle pre-divider first */
> > + if (prate != AC100_RTC_32K_RATE) {
> > + div = (reg >> AC100_CLKOUT_PRE_DIV_SHIFT) &
> > + ((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1);
> > + prate = divider_recalc_rate(hw, prate, div,
> > + ac100_clkout_prediv, 0);
> > + }
> > +
> > + div = (reg >> AC100_CLKOUT_DIV_SHIFT) &
> > + (BIT(AC100_CLKOUT_DIV_WIDTH) - 1);
> > + return divider_recalc_rate(hw, prate, div, NULL,
> > + CLK_DIVIDER_POWER_OF_TWO);
> > +}
> > +
> > +static long ac100_clkout_round_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long prate)
> > +{
> > + unsigned long best_rate = 0, tmp_rate, tmp_prate;
> > + int i;
> > +
> > + if (prate == AC100_RTC_32K_RATE)
> > + return divider_round_rate(hw, rate, &prate, NULL,
> > + AC100_CLKOUT_DIV_WIDTH,
> > + CLK_DIVIDER_POWER_OF_TWO);
> > +
> > + for (i = 0; ac100_clkout_prediv[i].div; i++) {
> > + tmp_prate = DIV_ROUND_UP(prate, ac100_clkout_prediv[i].val);
> > + tmp_rate = divider_round_rate(hw, rate, &tmp_prate, NULL,
> > + AC100_CLKOUT_DIV_WIDTH,
> > + CLK_DIVIDER_POWER_OF_TWO);
> > +
> > + if (tmp_rate > rate)
> > + continue;
> > + if (rate - tmp_rate < best_rate - tmp_rate)
> > + best_rate = tmp_rate;
> > + }
> > +
> > + return best_rate;
> > +}
> > +
> > +static int ac100_clkout_determine_rate(struct clk_hw *hw,
> > + struct clk_rate_request *req)
> > +{
> > + struct clk_hw *best_parent;
> > + unsigned long best = 0;
> > + int i, num_parents = clk_hw_get_num_parents(hw);
> > +
> > + for (i = 0; i < num_parents; i++) {
> > + struct clk_hw *parent = clk_hw_get_parent_by_index(hw, i);
> > + unsigned long tmp, prate = clk_hw_get_rate(parent);
> > +
> > + tmp = ac100_clkout_round_rate(hw, req->rate, prate);
> > +
> > + if (tmp > req->rate)
> > + continue;
> > + if (req->rate - tmp < req->rate - best) {
> > + best = tmp;
> > + best_parent = parent;
> > + }
> > + }
> > +
> > + if (!best)
> > + return -EINVAL;
> > +
> > + req->best_parent_hw = best_parent;
> > + req->best_parent_rate = best;
> > + req->rate = best;
> > +
> > + return 0;
> > +}
> > +
> > +static int ac100_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long prate)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > + int div = 0, pre_div = 0;
> > +
> > + do {
> > + div = divider_get_val(rate * ac100_clkout_prediv[pre_div].div,
> > + prate, NULL, AC100_CLKOUT_DIV_WIDTH,
> > + CLK_DIVIDER_POWER_OF_TWO);
> > + if (div >= 0)
> > + break;
> > + } while (prate != AC100_RTC_32K_RATE &&
> > + ac100_clkout_prediv[++pre_div].div);
> > +
> > + if (div < 0)
> > + return div;
> > +
> > + pre_div = ac100_clkout_prediv[pre_div].val;
> > +
> > + regmap_update_bits(clk->regmap, clk->offset,
> > + ((1 << AC100_CLKOUT_DIV_WIDTH) - 1) << AC100_CLKOUT_DIV_SHIFT |
> > + ((1 << AC100_CLKOUT_PRE_DIV_WIDTH) - 1) << AC100_CLKOUT_PRE_DIV_SHIFT,
> > + (div - 1) << AC100_CLKOUT_DIV_SHIFT |
> > + (pre_div - 1) << AC100_CLKOUT_PRE_DIV_SHIFT);
> > +
> > + return 0;
> > +}
> > +
> > +static int ac100_clkout_prepare(struct clk_hw *hw)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > +
> > + return regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN,
> > + AC100_CLKOUT_EN);
> > +}
> > +
> > +static void ac100_clkout_unprepare(struct clk_hw *hw)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > +
> > + regmap_update_bits(clk->regmap, clk->offset, AC100_CLKOUT_EN, 0);
> > +}
> > +
> > +static int ac100_clkout_is_prepared(struct clk_hw *hw)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > + unsigned int reg;
> > +
> > + regmap_read(clk->regmap, clk->offset, &reg);
> > +
> > + return reg & AC100_CLKOUT_EN;
> > +}
> > +
> > +static u8 ac100_clkout_get_parent(struct clk_hw *hw)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > + unsigned int reg;
> > +
> > + regmap_read(clk->regmap, clk->offset, &reg);
> > +
> > + return (reg >> AC100_CLKOUT_MUX_SHIFT) & 0x1;
> > +}
> > +
> > +static int ac100_clkout_set_parent(struct clk_hw *hw, u8 index)
> > +{
> > + struct ac100_clkout *clk = to_ac100_clkout(hw);
> > +
> > + return regmap_update_bits(clk->regmap, clk->offset,
> > + BIT(AC100_CLKOUT_MUX_SHIFT),
> > + index ? BIT(AC100_CLKOUT_MUX_SHIFT) : 0);
> > +}
> > +
> > +static const struct clk_ops ac100_clkout_ops = {
> > + .prepare = ac100_clkout_prepare,
> > + .unprepare = ac100_clkout_unprepare,
> > + .is_prepared = ac100_clkout_is_prepared,
> > + .recalc_rate = ac100_clkout_recalc_rate,
> > + .determine_rate = ac100_clkout_determine_rate,
> > + .get_parent = ac100_clkout_get_parent,
> > + .set_parent = ac100_clkout_set_parent,
> > + .set_rate = ac100_clkout_set_rate,
> > +};
> > +
> > +static int ac100_rtc_register_clks(struct ac100_rtc_dev *chip)
> > +{
> > + struct device_node *np = chip->dev->of_node;
> > + const char *parents[2] = {AC100_RTC_32K_NAME};
> > + int i, ret;
> > +
> > + chip->clk_data = devm_kzalloc(chip->dev, sizeof(*chip->clk_data) +
> > + sizeof(*chip->clk_data->hws) *
> > + AC100_CLKOUT_NUM,
> > + GFP_KERNEL);
> > + if (!chip->clk_data)
> > + return -ENOMEM;
> > +
> > + chip->rtc_32k_clk = clk_hw_register_fixed_rate(chip->dev,
> > + AC100_RTC_32K_NAME,
> > + NULL, 0,
> > + AC100_RTC_32K_RATE);
> > + if (IS_ERR(chip->rtc_32k_clk)) {
> > + ret = PTR_ERR(chip->rtc_32k_clk);
> > + dev_err(chip->dev, "Failed to register RTC-32k clock: %d\n",
> > + ret);
> > + return ret;
> > + }
> > +
> > + parents[1] = of_clk_get_parent_name(np, 0);
> > + if (!parents[1]) {
> > + dev_err(chip->dev, "Failed to get ADDA 4M clock\n");
> > + return -EINVAL;
> > + }
> > +
> > + for (i = 0; i < AC100_CLKOUT_NUM; i++) {
> > + struct ac100_clkout *clk = &chip->clks[i];
> > + struct clk_init_data init = {
> > + .name = ac100_clkout_names[i],
> > + .ops = &ac100_clkout_ops,
> > + .parent_names = parents,
> > + .num_parents = ARRAY_SIZE(parents),
> > + .flags = 0,
> > + };
> > +
> > + clk->regmap = chip->regmap;
> > + clk->offset = AC100_CLKOUT_CTRL1 + i;
> > + clk->hw.init = &init;
> > +
> > + ret = devm_clk_hw_register(chip->dev, &clk->hw);
> > + if (ret) {
> > + dev_err(chip->dev, "Failed to register clk '%s': %d\n",
> > + init.name, ret);
> > + goto err_unregister_rtc_32k;
> > + }
> > +
> > + chip->clk_data->hws[i] = &clk->hw;
> > + }
> > +
> > + chip->clk_data->num = i;
> > + ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, chip->clk_data);
> > + if (ret)
> > + goto err_unregister_rtc_32k;
> > +
> > + return 0;
> > +
> > +err_unregister_rtc_32k:
> > + clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
> > +
> > + return ret;
> > +}
> > +
> > +static void ac100_rtc_unregister_clks(struct ac100_rtc_dev *chip)
> > +{
> > + of_clk_del_provider(chip->dev->of_node);
> > + clk_unregister_fixed_rate(chip->rtc_32k_clk->clk);
> > +}
> > +
> > +/**
> > + * RTC related bits
> > + */
> > static int ac100_rtc_get_time(struct device *dev, struct rtc_time *rtc_tm)
> > {
> > struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
> > @@ -300,11 +588,24 @@ static int ac100_rtc_probe(struct platform_device *pdev)
> > return PTR_ERR(chip->rtc);
> > }
> >
> > + ret = ac100_rtc_register_clks(chip);
> > + if (ret)
> > + return ret;
> > +
> > dev_info(&pdev->dev, "RTC enabled\n");
> >
> > return 0;
> > }
> >
> > +static int ac100_rtc_remove(struct platform_device *pdev)
> > +{
> > + struct ac100_rtc_dev *chip = platform_get_drvdata(pdev);
> > +
> > + ac100_rtc_unregister_clks(chip);
> > +
> > + return 0;
> > +}
> > +
> > static const struct of_device_id ac100_rtc_match[] = {
> > { .compatible = "x-powers,ac100-rtc" },
> > { },
> > @@ -313,6 +614,7 @@ MODULE_DEVICE_TABLE(of, ac100_rtc_match);
> >
> > static struct platform_driver ac100_rtc_driver = {
> > .probe = ac100_rtc_probe,
> > + .remove = ac100_rtc_remove,
> > .driver = {
> > .name = "ac100-rtc",
> > .of_match_table = of_match_ptr(ac100_rtc_match),
>

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org â Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog