Commit 04940631 authored by Chen-Yu Tsai's avatar Chen-Yu Tsai Committed by Lee Jones
Browse files

rtc: ac100: Add clk output support 



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: default avatarChen-Yu Tsai <wens@csie.org>
Acked-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent d00a18a4

drivers/rtc/rtc-ac100.c

+302 −0
Original line number Diff line number Diff line
@@ -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),

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