clk: at91: add audio pll clock drivers

This new clock driver set allows to have a fractional divided clock that
would generate a precise clock particularly suitable for audio
applications.

The main audio pll clock has two children clocks: one that is connected
to the PMC, the other that can directly drive a pad. As these two routes
have different enable bits and different dividers and divider formulas,
they are handled by two different drivers. Each of them could modify the
rate of the main audio pll parent.

The main audio pll clock can output 620MHz to 700MHz.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 536 insertions, 0 deletions

diff --git a/drivers/clk/at91/clk-audio-pll.c b/drivers/clk/at91/clk-audio-pll.c
new file mode 100644
index 000000000000..da7bafcfbe70
--- /dev/null
+++ b/drivers/clk/at91/clk-audio-pll.c
@@ -0,0 +1,536 @@
+/*
+ *  Copyright (C) 2016 Atmel Corporation,
+ *		       Songjun Wu <songjun.wu@atmel.com>,
+ *                     Nicolas Ferre <nicolas.ferre@atmel.com>
+ *  Copyright (C) 2017 Free Electrons,
+ *		       Quentin Schulz <quentin.schulz@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * The Sama5d2 SoC has two audio PLLs (PMC and PAD) that shares the same parent
+ * (FRAC). FRAC can output between 620 and 700MHz and only multiply the rate of
+ * its own parent. PMC and PAD can then divide the FRAC rate to best match the
+ * asked rate.
+ *
+ * Traits of FRAC clock:
+ * enable - clk_enable writes nd, fracr parameters and enables PLL
+ * rate - rate is adjustable.
+ *        clk->rate = parent->rate * ((nd + 1) + (fracr / 2^22))
+ * parent - fixed parent.  No clk_set_parent support
+ *
+ * Traits of PMC clock:
+ * enable - clk_enable writes qdpmc, and enables PMC output
+ * rate - rate is adjustable.
+ *        clk->rate = parent->rate / (qdpmc + 1)
+ * parent - fixed parent.  No clk_set_parent support
+ *
+ * Traits of PAD clock:
+ * enable - clk_enable writes divisors and enables PAD output
+ * rate - rate is adjustable.
+ *        clk->rate = parent->rate / (qdaudio * div))
+ * parent - fixed parent.  No clk_set_parent support
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clk/at91_pmc.h>
+#include <linux/of.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define AUDIO_PLL_DIV_FRAC	BIT(22)
+#define AUDIO_PLL_ND_MAX	(AT91_PMC_AUDIO_PLL_ND_MASK >> \
+					AT91_PMC_AUDIO_PLL_ND_OFFSET)
+
+#define AUDIO_PLL_QDPAD(qd, div)	((AT91_PMC_AUDIO_PLL_QDPAD_EXTDIV(qd) & \
+					  AT91_PMC_AUDIO_PLL_QDPAD_EXTDIV_MASK) | \
+					 (AT91_PMC_AUDIO_PLL_QDPAD_DIV(div) & \
+					  AT91_PMC_AUDIO_PLL_QDPAD_DIV_MASK))
+
+#define AUDIO_PLL_QDPMC_MAX		(AT91_PMC_AUDIO_PLL_QDPMC_MASK >> \
+						AT91_PMC_AUDIO_PLL_QDPMC_OFFSET)
+
+#define AUDIO_PLL_FOUT_MIN	620000000UL
+#define AUDIO_PLL_FOUT_MAX	700000000UL
+
+struct clk_audio_frac {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	u32 fracr;
+	u8 nd;
+};
+
+struct clk_audio_pad {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	u8 qdaudio;
+	u8 div;
+};
+
+struct clk_audio_pmc {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	u8 qdpmc;
+};
+
+#define to_clk_audio_frac(hw) container_of(hw, struct clk_audio_frac, hw)
+#define to_clk_audio_pad(hw) container_of(hw, struct clk_audio_pad, hw)
+#define to_clk_audio_pmc(hw) container_of(hw, struct clk_audio_pmc, hw)
+
+static int clk_audio_pll_frac_enable(struct clk_hw *hw)
+{
+	struct clk_audio_frac *frac = to_clk_audio_frac(hw);
+
+	regmap_update_bits(frac->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_RESETN, 0);
+	regmap_update_bits(frac->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_RESETN,
+			   AT91_PMC_AUDIO_PLL_RESETN);
+	regmap_update_bits(frac->regmap, AT91_PMC_AUDIO_PLL1,
+			   AT91_PMC_AUDIO_PLL_FRACR_MASK, frac->fracr);
+
+	/*
+	 * reset and enable have to be done in 2 separated writes
+	 * for AT91_PMC_AUDIO_PLL0
+	 */
+	regmap_update_bits(frac->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_PLLEN |
+			   AT91_PMC_AUDIO_PLL_ND_MASK,
+			   AT91_PMC_AUDIO_PLL_PLLEN |
+			   AT91_PMC_AUDIO_PLL_ND(frac->nd));
+
+	return 0;
+}
+
+static int clk_audio_pll_pad_enable(struct clk_hw *hw)
+{
+	struct clk_audio_pad *apad_ck = to_clk_audio_pad(hw);
+
+	regmap_update_bits(apad_ck->regmap, AT91_PMC_AUDIO_PLL1,
+			   AT91_PMC_AUDIO_PLL_QDPAD_MASK,
+			   AUDIO_PLL_QDPAD(apad_ck->qdaudio, apad_ck->div));
+	regmap_update_bits(apad_ck->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_PADEN, AT91_PMC_AUDIO_PLL_PADEN);
+
+	return 0;
+}
+
+static int clk_audio_pll_pmc_enable(struct clk_hw *hw)
+{
+	struct clk_audio_pmc *apmc_ck = to_clk_audio_pmc(hw);
+
+	regmap_update_bits(apmc_ck->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_PMCEN |
+			   AT91_PMC_AUDIO_PLL_QDPMC_MASK,
+			   AT91_PMC_AUDIO_PLL_PMCEN |
+			   AT91_PMC_AUDIO_PLL_QDPMC(apmc_ck->qdpmc));
+	return 0;
+}
+
+static void clk_audio_pll_frac_disable(struct clk_hw *hw)
+{
+	struct clk_audio_frac *frac = to_clk_audio_frac(hw);
+
+	regmap_update_bits(frac->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_PLLEN, 0);
+	/* do it in 2 separated writes */
+	regmap_update_bits(frac->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_RESETN, 0);
+}
+
+static void clk_audio_pll_pad_disable(struct clk_hw *hw)
+{
+	struct clk_audio_pad *apad_ck = to_clk_audio_pad(hw);
+
+	regmap_update_bits(apad_ck->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_PADEN, 0);
+}
+
+static void clk_audio_pll_pmc_disable(struct clk_hw *hw)
+{
+	struct clk_audio_pmc *apmc_ck = to_clk_audio_pmc(hw);
+
+	regmap_update_bits(apmc_ck->regmap, AT91_PMC_AUDIO_PLL0,
+			   AT91_PMC_AUDIO_PLL_PMCEN, 0);
+}
+
+static unsigned long clk_audio_pll_fout(unsigned long parent_rate,
+					unsigned long nd, unsigned long fracr)
+{
+	unsigned long long fr = (unsigned long long)parent_rate * fracr;
+
+	pr_debug("A PLL: %s, fr = %llu\n", __func__, fr);
+
+	fr = DIV_ROUND_CLOSEST_ULL(fr, AUDIO_PLL_DIV_FRAC);
+
+	pr_debug("A PLL: %s, fr = %llu\n", __func__, fr);
+
+	return parent_rate * (nd + 1) + fr;
+}
+
+static unsigned long clk_audio_pll_frac_recalc_rate(struct clk_hw *hw,
+						    unsigned long parent_rate)
+{
+	struct clk_audio_frac *frac = to_clk_audio_frac(hw);
+	unsigned long fout;
+
+	fout = clk_audio_pll_fout(parent_rate, frac->nd, frac->fracr);
+
+	pr_debug("A PLL: %s, fout = %lu (nd = %u, fracr = %lu)\n", __func__,
+		 fout, frac->nd, (unsigned long)frac->fracr);
+
+	return fout;
+}
+
+static unsigned long clk_audio_pll_pad_recalc_rate(struct clk_hw *hw,
+						   unsigned long parent_rate)
+{
+	struct clk_audio_pad *apad_ck = to_clk_audio_pad(hw);
+	unsigned long apad_rate = 0;
+
+	if (apad_ck->qdaudio && apad_ck->div)
+		apad_rate = parent_rate / (apad_ck->qdaudio * apad_ck->div);
+
+	pr_debug("A PLL/PAD: %s, apad_rate = %lu (div = %u, qdaudio = %u)\n",
+		 __func__, apad_rate, apad_ck->div, apad_ck->qdaudio);
+
+	return apad_rate;
+}
+
+static unsigned long clk_audio_pll_pmc_recalc_rate(struct clk_hw *hw,
+						   unsigned long parent_rate)
+{
+	struct clk_audio_pmc *apmc_ck = to_clk_audio_pmc(hw);
+	unsigned long apmc_rate = 0;
+
+	apmc_rate = parent_rate / (apmc_ck->qdpmc + 1);
+
+	pr_debug("A PLL/PMC: %s, apmc_rate = %lu (qdpmc = %u)\n", __func__,
+		 apmc_rate, apmc_ck->qdpmc);
+
+	return apmc_rate;
+}
+
+static int clk_audio_pll_frac_compute_frac(unsigned long rate,
+					   unsigned long parent_rate,
+					   unsigned long *nd,
+					   unsigned long *fracr)
+{
+	unsigned long long tmp, rem;
+
+	if (!rate)
+		return -EINVAL;
+
+	tmp = rate;
+	rem = do_div(tmp, parent_rate);
+	if (!tmp || tmp >= AUDIO_PLL_ND_MAX)
+		return -EINVAL;
+
+	*nd = tmp - 1;
+
+	tmp = rem * AUDIO_PLL_DIV_FRAC;
+	tmp = DIV_ROUND_CLOSEST_ULL(tmp, parent_rate);
+	if (tmp > AT91_PMC_AUDIO_PLL_FRACR_MASK)
+		return -EINVAL;
+
+	/* we can cast here as we verified the bounds just above */
+	*fracr = (unsigned long)tmp;
+
+	return 0;
+}
+
+static int clk_audio_pll_frac_determine_rate(struct clk_hw *hw,
+					     struct clk_rate_request *req)
+{
+	unsigned long fracr, nd;
+	int ret;
+
+	pr_debug("A PLL: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 req->rate, req->best_parent_rate);
+
+	req->rate = clamp(req->rate, AUDIO_PLL_FOUT_MIN, AUDIO_PLL_FOUT_MAX);
+
+	req->min_rate = max(req->min_rate, AUDIO_PLL_FOUT_MIN);
+	req->max_rate = min(req->max_rate, AUDIO_PLL_FOUT_MAX);
+
+	ret = clk_audio_pll_frac_compute_frac(req->rate, req->best_parent_rate,
+					      &nd, &fracr);
+	if (ret)
+		return ret;
+
+	req->rate = clk_audio_pll_fout(req->best_parent_rate, nd, fracr);
+
+	req->best_parent_hw = clk_hw_get_parent(hw);
+
+	pr_debug("A PLL: %s, best_rate = %lu (nd = %lu, fracr = %lu)\n",
+		 __func__, req->rate, nd, fracr);
+
+	return 0;
+}
+
+static long clk_audio_pll_pad_round_rate(struct clk_hw *hw, unsigned long rate,
+					 unsigned long *parent_rate)
+{
+	struct clk_hw *pclk = clk_hw_get_parent(hw);
+	long best_rate = -EINVAL;
+	unsigned long best_parent_rate;
+	unsigned long tmp_qd;
+	u32 div;
+	long tmp_rate;
+	int tmp_diff;
+	int best_diff = -1;
+
+	pr_debug("A PLL/PAD: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 rate, *parent_rate);
+
+	/*
+	 * Rate divisor is actually made of two different divisors, multiplied
+	 * between themselves before dividing the rate.
+	 * tmp_qd goes from 1 to 31 and div is either 2 or 3.
+	 * In order to avoid testing twice the rate divisor (e.g. divisor 12 can
+	 * be found with (tmp_qd, div) = (2, 6) or (3, 4)), we remove any loop
+	 * for a rate divisor when div is 2 and tmp_qd is a multiple of 3.
+	 * We cannot inverse it (condition div is 3 and tmp_qd is even) or we
+	 * would miss some rate divisor that aren't reachable with div being 2
+	 * (e.g. rate divisor 90 is made with div = 3 and tmp_qd = 30, thus
+	 * tmp_qd is even so we skip it because we think div 2 could make this
+	 * rate divisor which isn't possible since tmp_qd has to be <= 31).
+	 */
+	for (tmp_qd = 1; tmp_qd < AT91_PMC_AUDIO_PLL_QDPAD_EXTDIV_MAX; tmp_qd++)
+		for (div = 2; div <= 3; div++) {
+			if (div == 2 && tmp_qd % 3 == 0)
+				continue;
+
+			best_parent_rate = clk_hw_round_rate(pclk,
+							rate * tmp_qd * div);
+			tmp_rate = best_parent_rate / (div * tmp_qd);
+			tmp_diff = abs(rate - tmp_rate);
+
+			if (best_diff < 0 || best_diff > tmp_diff) {
+				*parent_rate = best_parent_rate;
+				best_rate = tmp_rate;
+				best_diff = tmp_diff;
+			}
+		}
+
+	pr_debug("A PLL/PAD: %s, best_rate = %ld, best_parent_rate = %lu\n",
+		 __func__, best_rate, best_parent_rate);
+
+	return best_rate;
+}
+
+static long clk_audio_pll_pmc_round_rate(struct clk_hw *hw, unsigned long rate,
+					 unsigned long *parent_rate)
+{
+	struct clk_hw *pclk = clk_hw_get_parent(hw);
+	long best_rate = -EINVAL;
+	unsigned long best_parent_rate = 0;
+	u32 tmp_qd = 0, div;
+	long tmp_rate;
+	int tmp_diff;
+	int best_diff = -1;
+
+	pr_debug("A PLL/PMC: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 rate, *parent_rate);
+
+	for (div = 1; div <= AUDIO_PLL_QDPMC_MAX; div++) {
+		best_parent_rate = clk_round_rate(pclk->clk, rate * div);
+		tmp_rate = best_parent_rate / div;
+		tmp_diff = abs(rate - tmp_rate);
+
+		if (best_diff < 0 || best_diff > tmp_diff) {
+			*parent_rate = best_parent_rate;
+			best_rate = tmp_rate;
+			best_diff = tmp_diff;
+			tmp_qd = div;
+		}
+	}
+
+	pr_debug("A PLL/PMC: %s, best_rate = %ld, best_parent_rate = %lu (qd = %d)\n",
+		 __func__, best_rate, *parent_rate, tmp_qd - 1);
+
+	return best_rate;
+}
+
+static int clk_audio_pll_frac_set_rate(struct clk_hw *hw, unsigned long rate,
+				       unsigned long parent_rate)
+{
+	struct clk_audio_frac *frac = to_clk_audio_frac(hw);
+	unsigned long fracr, nd;
+	int ret;
+
+	pr_debug("A PLL: %s, rate = %lu (parent_rate = %lu)\n", __func__, rate,
+		 parent_rate);
+
+	if (rate < AUDIO_PLL_FOUT_MIN || rate > AUDIO_PLL_FOUT_MAX)
+		return -EINVAL;
+
+	ret = clk_audio_pll_frac_compute_frac(rate, parent_rate, &nd, &fracr);
+	if (ret)
+		return ret;
+
+	frac->nd = nd;
+	frac->fracr = fracr;
+
+	return 0;
+}
+
+static int clk_audio_pll_pad_set_rate(struct clk_hw *hw, unsigned long rate,
+				      unsigned long parent_rate)
+{
+	struct clk_audio_pad *apad_ck = to_clk_audio_pad(hw);
+	u8 tmp_div;
+
+	pr_debug("A PLL/PAD: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 rate, parent_rate);
+
+	if (!rate)
+		return -EINVAL;
+
+	tmp_div = parent_rate / rate;
+	if (tmp_div % 3 == 0) {
+		apad_ck->qdaudio = tmp_div / 3;
+		apad_ck->div = 3;
+	} else {
+		apad_ck->qdaudio = tmp_div / 2;
+		apad_ck->div = 2;
+	}
+
+	return 0;
+}
+
+static int clk_audio_pll_pmc_set_rate(struct clk_hw *hw, unsigned long rate,
+				      unsigned long parent_rate)
+{
+	struct clk_audio_pmc *apmc_ck = to_clk_audio_pmc(hw);
+
+	if (!rate)
+		return -EINVAL;
+
+	pr_debug("A PLL/PMC: %s, rate = %lu (parent_rate = %lu)\n", __func__,
+		 rate, parent_rate);
+
+	apmc_ck->qdpmc = parent_rate / rate - 1;
+
+	return 0;
+}
+
+static const struct clk_ops audio_pll_frac_ops = {
+	.enable = clk_audio_pll_frac_enable,
+	.disable = clk_audio_pll_frac_disable,
+	.recalc_rate = clk_audio_pll_frac_recalc_rate,
+	.determine_rate = clk_audio_pll_frac_determine_rate,
+	.set_rate = clk_audio_pll_frac_set_rate,
+};
+
+static const struct clk_ops audio_pll_pad_ops = {
+	.enable = clk_audio_pll_pad_enable,
+	.disable = clk_audio_pll_pad_disable,
+	.recalc_rate = clk_audio_pll_pad_recalc_rate,
+	.round_rate = clk_audio_pll_pad_round_rate,
+	.set_rate = clk_audio_pll_pad_set_rate,
+};
+
+static const struct clk_ops audio_pll_pmc_ops = {
+	.enable = clk_audio_pll_pmc_enable,
+	.disable = clk_audio_pll_pmc_disable,
+	.recalc_rate = clk_audio_pll_pmc_recalc_rate,
+	.round_rate = clk_audio_pll_pmc_round_rate,
+	.set_rate = clk_audio_pll_pmc_set_rate,
+};
+
+static int of_sama5d2_clk_audio_pll_setup(struct device_node *np,
+					  struct clk_init_data *init,
+					  struct clk_hw *hw,
+					  struct regmap **clk_audio_regmap)
+{
+	struct regmap *regmap;
+	const char *parent_names[1];
+	int ret;
+
+	regmap = syscon_node_to_regmap(of_get_parent(np));
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	init->name = np->name;
+	of_clk_parent_fill(np, parent_names, 1);
+	init->parent_names = parent_names;
+	init->num_parents = 1;
+
+	hw->init = init;
+	*clk_audio_regmap = regmap;
+
+	ret = clk_hw_register(NULL, hw);
+	if (ret)
+		return ret;
+
+	return of_clk_add_hw_provider(np, of_clk_hw_simple_get, hw);
+}
+
+static void __init of_sama5d2_clk_audio_pll_frac_setup(struct device_node *np)
+{
+	struct clk_audio_frac *frac_ck;
+	struct clk_init_data init = {};
+
+	frac_ck = kzalloc(sizeof(*frac_ck), GFP_KERNEL);
+	if (!frac_ck)
+		return;
+
+	init.ops = &audio_pll_frac_ops;
+	init.flags = CLK_SET_RATE_GATE;
+
+	if (of_sama5d2_clk_audio_pll_setup(np, &init, &frac_ck->hw,
+					   &frac_ck->regmap))
+		kfree(frac_ck);
+}
+
+static void __init of_sama5d2_clk_audio_pll_pad_setup(struct device_node *np)
+{
+	struct clk_audio_pad *apad_ck;
+	struct clk_init_data init = {};
+
+	apad_ck = kzalloc(sizeof(*apad_ck), GFP_KERNEL);
+	if (!apad_ck)
+		return;
+
+	init.ops = &audio_pll_pad_ops;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
+		CLK_SET_RATE_PARENT;
+
+	if (of_sama5d2_clk_audio_pll_setup(np, &init, &apad_ck->hw,
+					   &apad_ck->regmap))
+		kfree(apad_ck);
+}
+
+static void __init of_sama5d2_clk_audio_pll_pmc_setup(struct device_node *np)
+{
+	struct clk_audio_pad *apmc_ck;
+	struct clk_init_data init = {};
+
+	apmc_ck = kzalloc(sizeof(*apmc_ck), GFP_KERNEL);
+	if (!apmc_ck)
+		return;
+
+	init.ops = &audio_pll_pmc_ops;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
+		CLK_SET_RATE_PARENT;
+
+	if (of_sama5d2_clk_audio_pll_setup(np, &init, &apmc_ck->hw,
+					   &apmc_ck->regmap))
+		kfree(apmc_ck);
+}
+
+CLK_OF_DECLARE(of_sama5d2_clk_audio_pll_frac_setup,
+	       "atmel,sama5d2-clk-audio-pll-frac",
+	       of_sama5d2_clk_audio_pll_frac_setup);
+CLK_OF_DECLARE(of_sama5d2_clk_audio_pll_pad_setup,
+	       "atmel,sama5d2-clk-audio-pll-pad",
+	       of_sama5d2_clk_audio_pll_pad_setup);
+CLK_OF_DECLARE(of_sama5d2_clk_audio_pll_pmc_setup,
+	       "atmel,sama5d2-clk-audio-pll-pmc",
+	       of_sama5d2_clk_audio_pll_pmc_setup);