clk: qcom: Add support for High-Frequency PLLs (HFPLLs)

HFPLLs are the main frequency source for Krait CPU clocks. Add
support for changing the rate of these PLLs.

Signed-off-by: Stephen Boyd <[e-mail]>
Signed-off-by: Sricharan R <[e-mail]>
Tested-by: Craig Tatlor <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/qcom/Makefile

···
 clk-qcom-y += clk-regmap-divider.o
 clk-qcom-y += clk-regmap-mux.o
 clk-qcom-y += clk-regmap-mux-div.o
+clk-qcom-y += clk-hfpll.o
 clk-qcom-y += reset.o
 clk-qcom-$(CONFIG_QCOM_GDSC) += gdsc.o
 

drivers/clk/qcom/clk-hfpll.c

···
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/regmap.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/clk-provider.h>
+#include <linux/spinlock.h>
+
+#include "clk-regmap.h"
+#include "clk-hfpll.h"
+
+#define PLL_OUTCTRL	BIT(0)
+#define PLL_BYPASSNL	BIT(1)
+#define PLL_RESET_N	BIT(2)
+
+/* Initialize a HFPLL at a given rate and enable it. */
+static void __clk_hfpll_init_once(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+
+	if (likely(h->init_done))
+		return;
+
+	/* Configure PLL parameters for integer mode. */
+	if (hd->config_val)
+		regmap_write(regmap, hd->config_reg, hd->config_val);
+	regmap_write(regmap, hd->m_reg, 0);
+	regmap_write(regmap, hd->n_reg, 1);
+
+	if (hd->user_reg) {
+		u32 regval = hd->user_val;
+		unsigned long rate;
+
+		rate = clk_hw_get_rate(hw);
+
+		/* Pick the right VCO. */
+		if (hd->user_vco_mask && rate > hd->low_vco_max_rate)
+			regval |= hd->user_vco_mask;
+		regmap_write(regmap, hd->user_reg, regval);
+	}
+
+	if (hd->droop_reg)
+		regmap_write(regmap, hd->droop_reg, hd->droop_val);
+
+	h->init_done = true;
+}
+
+static void __clk_hfpll_enable(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 val;
+
+	__clk_hfpll_init_once(hw);
+
+	/* Disable PLL bypass mode. */
+	regmap_update_bits(regmap, hd->mode_reg, PLL_BYPASSNL, PLL_BYPASSNL);
+
+	/*
+	 * H/W requires a 5us delay between disabling the bypass and
+	 * de-asserting the reset. Delay 10us just to be safe.
+	 */
+	udelay(10);
+
+	/* De-assert active-low PLL reset. */
+	regmap_update_bits(regmap, hd->mode_reg, PLL_RESET_N, PLL_RESET_N);
+
+	/* Wait for PLL to lock. */
+	if (hd->status_reg) {
+		do {
+			regmap_read(regmap, hd->status_reg, &val);
+		} while (!(val & BIT(hd->lock_bit)));
+	} else {
+		udelay(60);
+	}
+
+	/* Enable PLL output. */
+	regmap_update_bits(regmap, hd->mode_reg, PLL_OUTCTRL, PLL_OUTCTRL);
+}
+
+/* Enable an already-configured HFPLL. */
+static int clk_hfpll_enable(struct clk_hw *hw)
+{
+	unsigned long flags;
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 mode;
+
+	spin_lock_irqsave(&h->lock, flags);
+	regmap_read(regmap, hd->mode_reg, &mode);
+	if (!(mode & (PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL)))
+		__clk_hfpll_enable(hw);
+	spin_unlock_irqrestore(&h->lock, flags);
+
+	return 0;
+}
+
+static void __clk_hfpll_disable(struct clk_hfpll *h)
+{
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+
+	/*
+	 * Disable the PLL output, disable test mode, enable the bypass mode,
+	 * and assert the reset.
+	 */
+	regmap_update_bits(regmap, hd->mode_reg,
+			   PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL, 0);
+}
+
+static void clk_hfpll_disable(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(&h->lock, flags);
+	__clk_hfpll_disable(h);
+	spin_unlock_irqrestore(&h->lock, flags);
+}
+
+static long clk_hfpll_round_rate(struct clk_hw *hw, unsigned long rate,
+				 unsigned long *parent_rate)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	unsigned long rrate;
+
+	rate = clamp(rate, hd->min_rate, hd->max_rate);
+
+	rrate = DIV_ROUND_UP(rate, *parent_rate) * *parent_rate;
+	if (rrate > hd->max_rate)
+		rrate -= *parent_rate;
+
+	return rrate;
+}
+
+/*
+ * For optimization reasons, assumes no downstream clocks are actively using
+ * it.
+ */
+static int clk_hfpll_set_rate(struct clk_hw *hw, unsigned long rate,
+			      unsigned long parent_rate)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	unsigned long flags;
+	u32 l_val, val;
+	bool enabled;
+
+	l_val = rate / parent_rate;
+
+	spin_lock_irqsave(&h->lock, flags);
+
+	enabled = __clk_is_enabled(hw->clk);
+	if (enabled)
+		__clk_hfpll_disable(h);
+
+	/* Pick the right VCO. */
+	if (hd->user_reg && hd->user_vco_mask) {
+		regmap_read(regmap, hd->user_reg, &val);
+		if (rate <= hd->low_vco_max_rate)
+			val &= ~hd->user_vco_mask;
+		else
+			val |= hd->user_vco_mask;
+		regmap_write(regmap, hd->user_reg, val);
+	}
+
+	regmap_write(regmap, hd->l_reg, l_val);
+
+	if (enabled)
+		__clk_hfpll_enable(hw);
+
+	spin_unlock_irqrestore(&h->lock, flags);
+
+	return 0;
+}
+
+static unsigned long clk_hfpll_recalc_rate(struct clk_hw *hw,
+					   unsigned long parent_rate)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 l_val;
+
+	regmap_read(regmap, hd->l_reg, &l_val);
+
+	return l_val * parent_rate;
+}
+
+static void clk_hfpll_init(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 mode, status;
+
+	regmap_read(regmap, hd->mode_reg, &mode);
+	if (mode != (PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL)) {
+		__clk_hfpll_init_once(hw);
+		return;
+	}
+
+	if (hd->status_reg) {
+		regmap_read(regmap, hd->status_reg, &status);
+		if (!(status & BIT(hd->lock_bit))) {
+			WARN(1, "HFPLL %s is ON, but not locked!\n",
+			     __clk_get_name(hw->clk));
+			clk_hfpll_disable(hw);
+			__clk_hfpll_init_once(hw);
+		}
+	}
+}
+
+static int hfpll_is_enabled(struct clk_hw *hw)
+{
+	struct clk_hfpll *h = to_clk_hfpll(hw);
+	struct hfpll_data const *hd = h->d;
+	struct regmap *regmap = h->clkr.regmap;
+	u32 mode;
+
+	regmap_read(regmap, hd->mode_reg, &mode);
+	mode &= 0x7;
+	return mode == (PLL_BYPASSNL | PLL_RESET_N | PLL_OUTCTRL);
+}
+
+const struct clk_ops clk_ops_hfpll = {
+	.enable = clk_hfpll_enable,
+	.disable = clk_hfpll_disable,
+	.is_enabled = hfpll_is_enabled,
+	.round_rate = clk_hfpll_round_rate,
+	.set_rate = clk_hfpll_set_rate,
+	.recalc_rate = clk_hfpll_recalc_rate,
+	.init = clk_hfpll_init,
+};
+EXPORT_SYMBOL_GPL(clk_ops_hfpll);

drivers/clk/qcom/clk-hfpll.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __QCOM_CLK_HFPLL_H__
+#define __QCOM_CLK_HFPLL_H__
+
+#include <linux/clk-provider.h>
+#include <linux/spinlock.h>
+#include "clk-regmap.h"
+
+struct hfpll_data {
+	u32 mode_reg;
+	u32 l_reg;
+	u32 m_reg;
+	u32 n_reg;
+	u32 user_reg;
+	u32 droop_reg;
+	u32 config_reg;
+	u32 status_reg;
+	u8  lock_bit;
+
+	u32 droop_val;
+	u32 config_val;
+	u32 user_val;
+	u32 user_vco_mask;
+	unsigned long low_vco_max_rate;
+
+	unsigned long min_rate;
+	unsigned long max_rate;
+};
+
+struct clk_hfpll {
+	struct hfpll_data const *d;
+	int init_done;
+
+	struct clk_regmap clkr;
+	spinlock_t lock;
+};
+
+#define to_clk_hfpll(_hw) \
+	container_of(to_clk_regmap(_hw), struct clk_hfpll, clkr)
+
+extern const struct clk_ops clk_ops_hfpll;
+
+#endif