clk: qcom: Add support for phase locked loops (PLLs)

Add support for Qualcomm's PLLs (phase locked loops). This is
sufficient enough to be able to determine the rate the PLL is
running at. We can add rate setting support later when it's
needed.

Signed-off-by: Stephen Boyd <[e-mail]>
Signed-off-by: Mike Turquette <[e-mail]>

drivers/clk/qcom/Makefile

···
 obj-$(CONFIG_COMMON_CLK_QCOM) += clk-qcom.o
 
 clk-qcom-$(CONFIG_COMMON_CLK_QCOM) += clk-regmap.o
+clk-qcom-$(CONFIG_COMMON_CLK_QCOM) += clk-pll.o

drivers/clk/qcom/clk-pll.c

···
+/*
+ * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/bug.h>
+#include <linux/delay.h>
+#include <linux/export.h>
+#include <linux/clk-provider.h>
+#include <linux/regmap.h>
+
+#include <asm/div64.h>
+
+#include "clk-pll.h"
+
+#define PLL_OUTCTRL		BIT(0)
+#define PLL_BYPASSNL		BIT(1)
+#define PLL_RESET_N		BIT(2)
+#define PLL_LOCK_COUNT_SHIFT	8
+#define PLL_LOCK_COUNT_MASK	0x3f
+#define PLL_BIAS_COUNT_SHIFT	14
+#define PLL_BIAS_COUNT_MASK	0x3f
+#define PLL_VOTE_FSM_ENA	BIT(20)
+#define PLL_VOTE_FSM_RESET	BIT(21)
+
+static int clk_pll_enable(struct clk_hw *hw)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	int ret;
+	u32 mask, val;
+
+	mask = PLL_OUTCTRL | PLL_RESET_N | PLL_BYPASSNL;
+	ret = regmap_read(pll->clkr.regmap, pll->mode_reg, &val);
+	if (ret)
+		return ret;
+
+	/* Skip if already enabled or in FSM mode */
+	if ((val & mask) == mask || val & PLL_VOTE_FSM_ENA)
+		return 0;
+
+	/* Disable PLL bypass mode. */
+	ret = regmap_update_bits(pll->clkr.regmap, pll->mode_reg, PLL_BYPASSNL,
+				 PLL_BYPASSNL);
+	if (ret)
+		return ret;
+
+	/*
+	 * 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. */
+	ret = regmap_update_bits(pll->clkr.regmap, pll->mode_reg, PLL_RESET_N,
+				 PLL_RESET_N);
+	if (ret)
+		return ret;
+
+	/* Wait until PLL is locked. */
+	udelay(50);
+
+	/* Enable PLL output. */
+	ret = regmap_update_bits(pll->clkr.regmap, pll->mode_reg, PLL_OUTCTRL,
+				 PLL_OUTCTRL);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void clk_pll_disable(struct clk_hw *hw)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	u32 mask;
+	u32 val;
+
+	regmap_read(pll->clkr.regmap, pll->mode_reg, &val);
+	/* Skip if in FSM mode */
+	if (val & PLL_VOTE_FSM_ENA)
+		return;
+	mask = PLL_OUTCTRL | PLL_RESET_N | PLL_BYPASSNL;
+	regmap_update_bits(pll->clkr.regmap, pll->mode_reg, mask, 0);
+}
+
+static unsigned long
+clk_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
+{
+	struct clk_pll *pll = to_clk_pll(hw);
+	u32 l, m, n;
+	unsigned long rate;
+	u64 tmp;
+
+	regmap_read(pll->clkr.regmap, pll->l_reg, &l);
+	regmap_read(pll->clkr.regmap, pll->m_reg, &m);
+	regmap_read(pll->clkr.regmap, pll->n_reg, &n);
+
+	l &= 0x3ff;
+	m &= 0x7ffff;
+	n &= 0x7ffff;
+
+	rate = parent_rate * l;
+	if (n) {
+		tmp = parent_rate;
+		tmp *= m;
+		do_div(tmp, n);
+		rate += tmp;
+	}
+	return rate;
+}
+
+const struct clk_ops clk_pll_ops = {
+	.enable = clk_pll_enable,
+	.disable = clk_pll_disable,
+	.recalc_rate = clk_pll_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(clk_pll_ops);
+
+static int wait_for_pll(struct clk_pll *pll)
+{
+	u32 val;
+	int count;
+	int ret;
+	const char *name = __clk_get_name(pll->clkr.hw.clk);
+
+	/* Wait for pll to enable. */
+	for (count = 200; count > 0; count--) {
+		ret = regmap_read(pll->clkr.regmap, pll->status_reg, &val);
+		if (ret)
+			return ret;
+		if (val & BIT(pll->status_bit))
+			return 0;
+		udelay(1);
+	}
+
+	WARN(1, "%s didn't enable after voting for it!\n", name);
+	return -ETIMEDOUT;
+}
+
+static int clk_pll_vote_enable(struct clk_hw *hw)
+{
+	int ret;
+	struct clk_pll *p = to_clk_pll(__clk_get_hw(__clk_get_parent(hw->clk)));
+
+	ret = clk_enable_regmap(hw);
+	if (ret)
+		return ret;
+
+	return wait_for_pll(p);
+}
+
+const struct clk_ops clk_pll_vote_ops = {
+	.enable = clk_pll_vote_enable,
+	.disable = clk_disable_regmap,
+};
+EXPORT_SYMBOL_GPL(clk_pll_vote_ops);
+
+static void
+clk_pll_set_fsm_mode(struct clk_pll *pll, struct regmap *regmap)
+{
+	u32 val;
+	u32 mask;
+
+	/* De-assert reset to FSM */
+	regmap_update_bits(regmap, pll->mode_reg, PLL_VOTE_FSM_RESET, 0);
+
+	/* Program bias count and lock count */
+	val = 1 << PLL_BIAS_COUNT_SHIFT;
+	mask = PLL_BIAS_COUNT_MASK << PLL_BIAS_COUNT_SHIFT;
+	mask |= PLL_LOCK_COUNT_MASK << PLL_LOCK_COUNT_SHIFT;
+	regmap_update_bits(regmap, pll->mode_reg, mask, val);
+
+	/* Enable PLL FSM voting */
+	regmap_update_bits(regmap, pll->mode_reg, PLL_VOTE_FSM_ENA,
+		PLL_VOTE_FSM_ENA);
+}
+
+static void clk_pll_configure(struct clk_pll *pll, struct regmap *regmap,
+	const struct pll_config *config)
+{
+	u32 val;
+	u32 mask;
+
+	regmap_write(regmap, pll->l_reg, config->l);
+	regmap_write(regmap, pll->m_reg, config->m);
+	regmap_write(regmap, pll->n_reg, config->n);
+
+	val = config->vco_val;
+	val |= config->pre_div_val;
+	val |= config->post_div_val;
+	val |= config->mn_ena_mask;
+	val |= config->main_output_mask;
+	val |= config->aux_output_mask;
+
+	mask = config->vco_mask;
+	mask |= config->pre_div_mask;
+	mask |= config->post_div_mask;
+	mask |= config->mn_ena_mask;
+	mask |= config->main_output_mask;
+	mask |= config->aux_output_mask;
+
+	regmap_update_bits(regmap, pll->config_reg, mask, val);
+}
+
+void clk_pll_configure_sr_hpm_lp(struct clk_pll *pll, struct regmap *regmap,
+		const struct pll_config *config, bool fsm_mode)
+{
+	clk_pll_configure(pll, regmap, config);
+	if (fsm_mode)
+		clk_pll_set_fsm_mode(pll, regmap);
+}
+EXPORT_SYMBOL_GPL(clk_pll_configure_sr_hpm_lp);

drivers/clk/qcom/clk-pll.h

···
+/*
+ * Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __QCOM_CLK_PLL_H__
+#define __QCOM_CLK_PLL_H__
+
+#include <linux/clk-provider.h>
+#include "clk-regmap.h"
+
+/**
+ * struct clk_pll - phase locked loop (PLL)
+ * @l_reg: L register
+ * @m_reg: M register
+ * @n_reg: N register
+ * @config_reg: config register
+ * @mode_reg: mode register
+ * @status_reg: status register
+ * @status_bit: ANDed with @status_reg to determine if PLL is enabled
+ * @hw: handle between common and hardware-specific interfaces
+ */
+struct clk_pll {
+	u32	l_reg;
+	u32	m_reg;
+	u32	n_reg;
+	u32	config_reg;
+	u32	mode_reg;
+	u32	status_reg;
+	u8	status_bit;
+
+	struct clk_regmap clkr;
+};
+
+extern const struct clk_ops clk_pll_ops;
+extern const struct clk_ops clk_pll_vote_ops;
+
+#define to_clk_pll(_hw) container_of(to_clk_regmap(_hw), struct clk_pll, clkr)
+
+struct pll_config {
+	u16 l;
+	u32 m;
+	u32 n;
+	u32 vco_val;
+	u32 vco_mask;
+	u32 pre_div_val;
+	u32 pre_div_mask;
+	u32 post_div_val;
+	u32 post_div_mask;
+	u32 mn_ena_mask;
+	u32 main_output_mask;
+	u32 aux_output_mask;
+};
+
+void clk_pll_configure_sr_hpm_lp(struct clk_pll *pll, struct regmap *regmap,
+		const struct pll_config *config, bool fsm_mode);
+
+#endif