clk: at91: add sam9x60 PLL driver

The PLLs on the sam9x60 (PLLA and USB PLL) use a different register set and
programming model than the previous SoCs.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 330 insertions, 0 deletions

diff --git a/drivers/clk/at91/clk-sam9x60-pll.c b/drivers/clk/at91/clk-sam9x60-pll.c
new file mode 100644
index 000000000000..34b817825b22
--- /dev/null
+++ b/drivers/clk/at91/clk-sam9x60-pll.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  Copyright (C) 2019 Microchip Technology Inc.
+ *
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/at91_pmc.h>
+#include <linux/of.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+#include "pmc.h"
+
+#define PMC_PLL_CTRL0	0xc
+#define		PMC_PLL_CTRL0_DIV_MSK		GENMASK(7, 0)
+#define		PMC_PLL_CTRL0_ENPLL		BIT(28)
+#define		PMC_PLL_CTRL0_ENPLLCK		BIT(29)
+#define		PMC_PLL_CTRL0_ENLOCK		BIT(31)
+
+#define PMC_PLL_CTRL1	0x10
+#define		PMC_PLL_CTRL1_FRACR_MSK		GENMASK(21, 0)
+#define		PMC_PLL_CTRL1_MUL_MSK		GENMASK(30, 24)
+
+#define PMC_PLL_ACR	0x18
+#define		PMC_PLL_ACR_DEFAULT		0x1b040010UL
+#define		PMC_PLL_ACR_UTMIVR		BIT(12)
+#define		PMC_PLL_ACR_UTMIBG		BIT(13)
+#define		PMC_PLL_ACR_LOOP_FILTER_MSK	GENMASK(31, 24)
+
+#define PMC_PLL_UPDT	0x1c
+#define		PMC_PLL_UPDT_UPDATE		BIT(8)
+
+#define PMC_PLL_ISR0	0xec
+
+#define PLL_DIV_MAX		(FIELD_GET(PMC_PLL_CTRL0_DIV_MSK, UINT_MAX) + 1)
+#define UPLL_DIV		2
+#define PLL_MUL_MAX		(FIELD_GET(PMC_PLL_CTRL1_MUL_MSK, UINT_MAX) + 1)
+
+#define PLL_MAX_ID		1
+
+struct sam9x60_pll {
+	struct clk_hw hw;
+	struct regmap *regmap;
+	spinlock_t *lock;
+	const struct clk_pll_characteristics *characteristics;
+	u32 frac;
+	u8 id;
+	u8 div;
+	u16 mul;
+};
+
+#define to_sam9x60_pll(hw) container_of(hw, struct sam9x60_pll, hw)
+
+static inline bool sam9x60_pll_ready(struct regmap *regmap, int id)
+{
+	unsigned int status;
+
+	regmap_read(regmap, PMC_PLL_ISR0, &status);
+
+	return !!(status & BIT(id));
+}
+
+static int sam9x60_pll_prepare(struct clk_hw *hw)
+{
+	struct sam9x60_pll *pll = to_sam9x60_pll(hw);
+	struct regmap *regmap = pll->regmap;
+	unsigned long flags;
+	u8 div;
+	u16 mul;
+	u32 val;
+
+	spin_lock_irqsave(pll->lock, flags);
+	regmap_write(regmap, PMC_PLL_UPDT, pll->id);
+
+	regmap_read(regmap, PMC_PLL_CTRL0, &val);
+	div = FIELD_GET(PMC_PLL_CTRL0_DIV_MSK, val);
+
+	regmap_read(regmap, PMC_PLL_CTRL1, &val);
+	mul = FIELD_GET(PMC_PLL_CTRL1_MUL_MSK, val);
+
+	if (sam9x60_pll_ready(regmap, pll->id) &&
+	    (div == pll->div && mul == pll->mul)) {
+		spin_unlock_irqrestore(pll->lock, flags);
+		return 0;
+	}
+
+	/* Recommended value for PMC_PLL_ACR */
+	val = PMC_PLL_ACR_DEFAULT;
+	regmap_write(regmap, PMC_PLL_ACR, val);
+
+	regmap_write(regmap, PMC_PLL_CTRL1,
+		     FIELD_PREP(PMC_PLL_CTRL1_MUL_MSK, pll->mul));
+
+	if (pll->characteristics->upll) {
+		/* Enable the UTMI internal bandgap */
+		val |= PMC_PLL_ACR_UTMIBG;
+		regmap_write(regmap, PMC_PLL_ACR, val);
+
+		udelay(10);
+
+		/* Enable the UTMI internal regulator */
+		val |= PMC_PLL_ACR_UTMIVR;
+		regmap_write(regmap, PMC_PLL_ACR, val);
+
+		udelay(10);
+	}
+
+	regmap_update_bits(regmap, PMC_PLL_UPDT,
+			   PMC_PLL_UPDT_UPDATE, PMC_PLL_UPDT_UPDATE);
+
+	regmap_write(regmap, PMC_PLL_CTRL0,
+		     PMC_PLL_CTRL0_ENLOCK | PMC_PLL_CTRL0_ENPLL |
+		     PMC_PLL_CTRL0_ENPLLCK | pll->div);
+
+	regmap_update_bits(regmap, PMC_PLL_UPDT,
+			   PMC_PLL_UPDT_UPDATE, PMC_PLL_UPDT_UPDATE);
+
+	while (!sam9x60_pll_ready(regmap, pll->id))
+		cpu_relax();
+
+	spin_unlock_irqrestore(pll->lock, flags);
+
+	return 0;
+}
+
+static int sam9x60_pll_is_prepared(struct clk_hw *hw)
+{
+	struct sam9x60_pll *pll = to_sam9x60_pll(hw);
+
+	return sam9x60_pll_ready(pll->regmap, pll->id);
+}
+
+static void sam9x60_pll_unprepare(struct clk_hw *hw)
+{
+	struct sam9x60_pll *pll = to_sam9x60_pll(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(pll->lock, flags);
+
+	regmap_write(pll->regmap, PMC_PLL_UPDT, pll->id);
+
+	regmap_update_bits(pll->regmap, PMC_PLL_CTRL0,
+			   PMC_PLL_CTRL0_ENPLLCK, 0);
+
+	regmap_update_bits(pll->regmap, PMC_PLL_UPDT,
+			   PMC_PLL_UPDT_UPDATE, PMC_PLL_UPDT_UPDATE);
+
+	regmap_update_bits(pll->regmap, PMC_PLL_CTRL0, PMC_PLL_CTRL0_ENPLL, 0);
+
+	if (pll->characteristics->upll)
+		regmap_update_bits(pll->regmap, PMC_PLL_ACR,
+				   PMC_PLL_ACR_UTMIBG | PMC_PLL_ACR_UTMIVR, 0);
+
+	regmap_update_bits(pll->regmap, PMC_PLL_UPDT,
+			   PMC_PLL_UPDT_UPDATE, PMC_PLL_UPDT_UPDATE);
+
+	spin_unlock_irqrestore(pll->lock, flags);
+}
+
+static unsigned long sam9x60_pll_recalc_rate(struct clk_hw *hw,
+					     unsigned long parent_rate)
+{
+	struct sam9x60_pll *pll = to_sam9x60_pll(hw);
+
+	return (parent_rate * (pll->mul + 1)) / (pll->div + 1);
+}
+
+static long sam9x60_pll_get_best_div_mul(struct sam9x60_pll *pll,
+					 unsigned long rate,
+					 unsigned long parent_rate,
+					 bool update)
+{
+	const struct clk_pll_characteristics *characteristics =
+							pll->characteristics;
+	unsigned long bestremainder = ULONG_MAX;
+	unsigned long maxdiv, mindiv, tmpdiv;
+	long bestrate = -ERANGE;
+	unsigned long bestdiv = 0;
+	unsigned long bestmul = 0;
+	unsigned long bestfrac = 0;
+
+	if (rate < characteristics->output[0].min ||
+	    rate > characteristics->output[0].max)
+		return -ERANGE;
+
+	if (!pll->characteristics->upll) {
+		mindiv = parent_rate / rate;
+		if (mindiv < 2)
+			mindiv = 2;
+
+		maxdiv = DIV_ROUND_UP(parent_rate * PLL_MUL_MAX, rate);
+		if (maxdiv > PLL_DIV_MAX)
+			maxdiv = PLL_DIV_MAX;
+	} else {
+		mindiv = maxdiv = UPLL_DIV;
+	}
+
+	for (tmpdiv = mindiv; tmpdiv <= maxdiv; tmpdiv++) {
+		unsigned long remainder;
+		unsigned long tmprate;
+		unsigned long tmpmul;
+		unsigned long tmpfrac = 0;
+
+		/*
+		 * Calculate the multiplier associated with the current
+		 * divider that provide the closest rate to the requested one.
+		 */
+		tmpmul = mult_frac(rate, tmpdiv, parent_rate);
+		tmprate = mult_frac(parent_rate, tmpmul, tmpdiv);
+		remainder = rate - tmprate;
+
+		if (remainder) {
+			tmpfrac = DIV_ROUND_CLOSEST_ULL((u64)remainder * tmpdiv * (1 << 22),
+							parent_rate);
+
+			tmprate += DIV_ROUND_CLOSEST_ULL((u64)tmpfrac * parent_rate,
+							 tmpdiv * (1 << 22));
+
+			if (tmprate > rate)
+				remainder = tmprate - rate;
+			else
+				remainder = rate - tmprate;
+		}
+
+		/*
+		 * Compare the remainder with the best remainder found until
+		 * now and elect a new best multiplier/divider pair if the
+		 * current remainder is smaller than the best one.
+		 */
+		if (remainder < bestremainder) {
+			bestremainder = remainder;
+			bestdiv = tmpdiv;
+			bestmul = tmpmul;
+			bestrate = tmprate;
+			bestfrac = tmpfrac;
+		}
+
+		/* We've found a perfect match!  */
+		if (!remainder)
+			break;
+	}
+
+	/* Check if bestrate is a valid output rate  */
+	if (bestrate < characteristics->output[0].min &&
+	    bestrate > characteristics->output[0].max)
+		return -ERANGE;
+
+	if (update) {
+		pll->div = bestdiv - 1;
+		pll->mul = bestmul - 1;
+		pll->frac = bestfrac;
+	}
+
+	return bestrate;
+}
+
+static long sam9x60_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long *parent_rate)
+{
+	struct sam9x60_pll *pll = to_sam9x60_pll(hw);
+
+	return sam9x60_pll_get_best_div_mul(pll, rate, *parent_rate, false);
+}
+
+static int sam9x60_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct sam9x60_pll *pll = to_sam9x60_pll(hw);
+
+	return sam9x60_pll_get_best_div_mul(pll, rate, parent_rate, true);
+}
+
+static const struct clk_ops pll_ops = {
+	.prepare = sam9x60_pll_prepare,
+	.unprepare = sam9x60_pll_unprepare,
+	.is_prepared = sam9x60_pll_is_prepared,
+	.recalc_rate = sam9x60_pll_recalc_rate,
+	.round_rate = sam9x60_pll_round_rate,
+	.set_rate = sam9x60_pll_set_rate,
+};
+
+struct clk_hw * __init
+sam9x60_clk_register_pll(struct regmap *regmap, spinlock_t *lock,
+			 const char *name, const char *parent_name, u8 id,
+			 const struct clk_pll_characteristics *characteristics)
+{
+	struct sam9x60_pll *pll;
+	struct clk_hw *hw;
+	struct clk_init_data init;
+	unsigned int pllr;
+	int ret;
+
+	if (id > PLL_MAX_ID)
+		return ERR_PTR(-EINVAL);
+
+	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+	if (!pll)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &pll_ops;
+	init.parent_names = &parent_name;
+	init.num_parents = 1;
+	init.flags = CLK_SET_RATE_GATE;
+
+	pll->id = id;
+	pll->hw.init = &init;
+	pll->characteristics = characteristics;
+	pll->regmap = regmap;
+	pll->lock = lock;
+
+	regmap_write(regmap, PMC_PLL_UPDT, id);
+	regmap_read(regmap, PMC_PLL_CTRL0, &pllr);
+	pll->div = FIELD_GET(PMC_PLL_CTRL0_DIV_MSK, pllr);
+	regmap_read(regmap, PMC_PLL_CTRL1, &pllr);
+	pll->mul = FIELD_GET(PMC_PLL_CTRL1_MUL_MSK, pllr);
+
+	hw = &pll->hw;
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		kfree(pll);
+		hw = ERR_PTR(ret);
+	}
+
+	return hw;
+}
+