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Commit 0cb937dc authored by Amit Nischal's avatar Amit Nischal Committed by Gerrit - the friendly Code Review server
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clk: qcom: Add support to calibrate fabia PLL 



Fabia PLL requires self on cablibration whenever it comes
out of reset. Add support to calibrate the pll by checking
calibration status.

Change-Id: I3c2a314a8ea109292174b0b3de430ba456d35d76
Signed-off-by: default avatarAmit Nischal <anischal@codeaurora.org>
parent 24af5c26

drivers/clk/qcom/clk-alpha-pll.c

+61 −0
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ 
#define REGERA_PLL_OUT_MASK	0x9



/* FABIA PLL specific settings and offsets */

#define FABIA_CAL_L_VAL		0x8

#define FABIA_USER_CTL_LO	0xc

#define FABIA_USER_CTL_HI	0x10

#define FABIA_CONFIG_CTL_LO	0x14
@@ -1875,6 +1876,65 @@ static void clk_fabia_pll_disable(struct clk_hw *hw) 
	regmap_write(pll->clkr.regmap, off + FABIA_OPMODE, FABIA_PLL_STANDBY);

}



/*

 * Fabia PLL requires power-on self calibration which happen when the PLL comes

 * out of reset. Calibration frequency is calculated by below relation:

 *

 * calibration freq = ((pll_l_valmax + pll_l_valmin) * 0.54)

 */

static int clk_fabia_pll_prepare(struct clk_hw *hw)

{

	unsigned long calibration_freq, freq_hz;

	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);

	const struct pll_vco *vco;

	u64 a;

	u32 cal_l, regval, off = pll->offset;

	int ret;



	/* Check if calibration needs to be done i.e. PLL is in reset */

	ret = regmap_read(pll->clkr.regmap, off + PLL_MODE, &regval);

	if (ret)

		return ret;



	/* Return early if calibration is not needed. */

	if (regval & PLL_RESET_N)

		return 0;



	vco = alpha_pll_find_vco(pll, clk_hw_get_rate(hw));

	if (!vco) {

		pr_err("alpha pll: not in a valid vco range\n");

		return -EINVAL;

	}



	calibration_freq = ((pll->vco_table[0].min_freq +

				pll->vco_table[0].max_freq) * 54)/100;



	freq_hz = alpha_pll_round_rate(pll, calibration_freq,

			clk_hw_get_rate(clk_hw_get_parent(hw)), &cal_l, &a);

	/*

	 * Due to a limited number of bits for fractional rate programming, the

	 * rounded up rate could be marginally higher than the requested rate.

	 */

	if (freq_hz > (calibration_freq + FABIA_PLL_RATE_MARGIN) ||

						freq_hz < calibration_freq) {

		pr_err("fabia_pll: Call set rate with rounded rates!\n");

		return -EINVAL;

	}



	/* Setup PLL for calibration frequency */

	regmap_write(pll->clkr.regmap, pll->offset + FABIA_CAL_L_VAL, cal_l);



	/* Bringup the pll at calibration frequency */

	ret = clk_fabia_pll_enable(hw);

	if (ret) {

		pr_err("alpha pll calibration failed\n");

		return ret;

	}



	clk_fabia_pll_disable(hw);

	return 0;

}



static unsigned long

clk_fabia_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)

{
@@ -1956,6 +2016,7 @@ static void clk_fabia_pll_list_registers(struct seq_file *f, struct clk_hw *hw) 
}



const struct clk_ops clk_fabia_pll_ops = {

	.prepare = clk_fabia_pll_prepare,

	.enable = clk_fabia_pll_enable,

	.disable = clk_fabia_pll_disable,

	.recalc_rate = clk_fabia_pll_recalc_rate,