ARM: 6014/1: ST SPEAr: Added clock framework for SPEAr platform and machines

Clock framework for SPEAr is based upon clkdev framework for ARM

Reviewed-by: Linus Walleij <linux.walleij@stericsson.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 581 insertions, 0 deletions

diff --git a/arch/arm/plat-spear/clock.c b/arch/arm/plat-spear/clock.c
new file mode 100644
index 000000000000..ee4f90e534d8
--- /dev/null
+++ b/arch/arm/plat-spear/clock.c
@@ -0,0 +1,435 @@
+/*
+ * arch/arm/plat-spear/clock.c
+ *
+ * Clock framework for SPEAr platform
+ *
+ * Copyright (C) 2009 ST Microelectronics
+ * Viresh Kumar<viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/bug.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <mach/misc_regs.h>
+#include <plat/clock.h>
+
+static DEFINE_SPINLOCK(clocks_lock);
+static LIST_HEAD(root_clks);
+
+static void propagate_rate(struct list_head *);
+
+static int generic_clk_enable(struct clk *clk)
+{
+	unsigned int val;
+
+	if (!clk->en_reg)
+		return -EFAULT;
+
+	val = readl(clk->en_reg);
+	if (unlikely(clk->flags & RESET_TO_ENABLE))
+		val &= ~(1 << clk->en_reg_bit);
+	else
+		val |= 1 << clk->en_reg_bit;
+
+	writel(val, clk->en_reg);
+
+	return 0;
+}
+
+static void generic_clk_disable(struct clk *clk)
+{
+	unsigned int val;
+
+	if (!clk->en_reg)
+		return;
+
+	val = readl(clk->en_reg);
+	if (unlikely(clk->flags & RESET_TO_ENABLE))
+		val |= 1 << clk->en_reg_bit;
+	else
+		val &= ~(1 << clk->en_reg_bit);
+
+	writel(val, clk->en_reg);
+}
+
+/* generic clk ops */
+static struct clkops generic_clkops = {
+	.enable = generic_clk_enable,
+	.disable = generic_clk_disable,
+};
+
+/*
+ * clk_enable - inform the system when the clock source should be running.
+ * @clk: clock source
+ *
+ * If the clock can not be enabled/disabled, this should return success.
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_enable(struct clk *clk)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	if (!clk || IS_ERR(clk))
+		return -EFAULT;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	if (clk->usage_count == 0) {
+		if (clk->ops && clk->ops->enable)
+			ret = clk->ops->enable(clk);
+	}
+	clk->usage_count++;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(clk_enable);
+
+/*
+ * clk_disable - inform the system when the clock source is no longer required.
+ * @clk: clock source
+ *
+ * Inform the system that a clock source is no longer required by
+ * a driver and may be shut down.
+ *
+ * Implementation detail: if the clock source is shared between
+ * multiple drivers, clk_enable() calls must be balanced by the
+ * same number of clk_disable() calls for the clock source to be
+ * disabled.
+ */
+void clk_disable(struct clk *clk)
+{
+	unsigned long flags;
+
+	if (!clk || IS_ERR(clk))
+		return;
+
+	WARN_ON(clk->usage_count == 0);
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	clk->usage_count--;
+	if (clk->usage_count == 0) {
+		if (clk->ops && clk->ops->disable)
+			clk->ops->disable(clk);
+	}
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+EXPORT_SYMBOL(clk_disable);
+
+/**
+ * clk_get_rate - obtain the current clock rate (in Hz) for a clock source.
+ *		 This is only valid once the clock source has been enabled.
+ * @clk: clock source
+ */
+unsigned long clk_get_rate(struct clk *clk)
+{
+	unsigned long flags, rate;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	rate = clk->rate;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+
+	return rate;
+}
+EXPORT_SYMBOL(clk_get_rate);
+
+/**
+ * clk_set_parent - set the parent clock source for this clock
+ * @clk: clock source
+ * @parent: parent clock source
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_parent(struct clk *clk, struct clk *parent)
+{
+	int i, found = 0, val = 0;
+	unsigned long flags;
+
+	if (!clk || IS_ERR(clk) || !parent || IS_ERR(parent))
+		return -EFAULT;
+	if (clk->usage_count)
+		return -EBUSY;
+	if (!clk->pclk_sel)
+		return -EPERM;
+	if (clk->pclk == parent)
+		return 0;
+
+	for (i = 0; i < clk->pclk_sel->pclk_count; i++) {
+		if (clk->pclk_sel->pclk_info[i].pclk == parent) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (!found)
+		return -EINVAL;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	/* reflect parent change in hardware */
+	val = readl(clk->pclk_sel->pclk_sel_reg);
+	val &= ~(clk->pclk_sel->pclk_sel_mask << clk->pclk_sel_shift);
+	val |= clk->pclk_sel->pclk_info[i].pclk_mask << clk->pclk_sel_shift;
+	writel(val, clk->pclk_sel->pclk_sel_reg);
+	spin_unlock_irqrestore(&clocks_lock, flags);
+
+	/* reflect parent change in software */
+	clk->recalc(clk);
+	propagate_rate(&clk->children);
+	return 0;
+}
+EXPORT_SYMBOL(clk_set_parent);
+
+/* registers clock in platform clock framework */
+void clk_register(struct clk_lookup *cl)
+{
+	struct clk *clk = cl->clk;
+	unsigned long flags;
+
+	if (!clk || IS_ERR(clk))
+		return;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+
+	INIT_LIST_HEAD(&clk->children);
+	if (clk->flags & ALWAYS_ENABLED)
+		clk->ops = NULL;
+	else if (!clk->ops)
+		clk->ops = &generic_clkops;
+
+	/* root clock don't have any parents */
+	if (!clk->pclk && !clk->pclk_sel) {
+		list_add(&clk->sibling, &root_clks);
+		/* add clocks with only one parent to parent's children list */
+	} else if (clk->pclk && !clk->pclk_sel) {
+		list_add(&clk->sibling, &clk->pclk->children);
+	} else {
+		/* add clocks with > 1 parent to 1st parent's children list */
+		list_add(&clk->sibling,
+			 &clk->pclk_sel->pclk_info[0].pclk->children);
+	}
+	spin_unlock_irqrestore(&clocks_lock, flags);
+
+	/* add clock to arm clockdev framework */
+	clkdev_add(cl);
+}
+
+/**
+ * propagate_rate - recalculate and propagate all clocks in list head
+ *
+ * Recalculates all root clocks in list head, which if the clock's .recalc is
+ * set correctly, should also propagate their rates.
+ */
+static void propagate_rate(struct list_head *lhead)
+{
+	struct clk *clkp, *_temp;
+
+	list_for_each_entry_safe(clkp, _temp, lhead, sibling) {
+		if (clkp->recalc)
+			clkp->recalc(clkp);
+		propagate_rate(&clkp->children);
+	}
+}
+
+/* returns current programmed clocks clock info structure */
+static struct pclk_info *pclk_info_get(struct clk *clk)
+{
+	unsigned int mask, i;
+	unsigned long flags;
+	struct pclk_info *info = NULL;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	mask = (readl(clk->pclk_sel->pclk_sel_reg) >> clk->pclk_sel_shift)
+			& clk->pclk_sel->pclk_sel_mask;
+
+	for (i = 0; i < clk->pclk_sel->pclk_count; i++) {
+		if (clk->pclk_sel->pclk_info[i].pclk_mask == mask)
+			info = &clk->pclk_sel->pclk_info[i];
+	}
+	spin_unlock_irqrestore(&clocks_lock, flags);
+
+	return info;
+}
+
+/*
+ * Set pclk as cclk's parent and add clock sibling node to current parents
+ * children list
+ */
+static void change_parent(struct clk *cclk, struct clk *pclk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	list_del(&cclk->sibling);
+	list_add(&cclk->sibling, &pclk->children);
+
+	cclk->pclk = pclk;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+
+/*
+ * calculates current programmed rate of pll1
+ *
+ * In normal mode
+ * rate = (2 * M[15:8] * Fin)/(N * 2^P)
+ *
+ * In Dithered mode
+ * rate = (2 * M[15:0] * Fin)/(256 * N * 2^P)
+ */
+void pll1_clk_recalc(struct clk *clk)
+{
+	struct pll_clk_config *config = clk->private_data;
+	unsigned int num = 2, den = 0, val, mode = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	mode = (readl(config->mode_reg) >> PLL_MODE_SHIFT) &
+		PLL_MODE_MASK;
+
+	val = readl(config->cfg_reg);
+	/* calculate denominator */
+	den = (val >> PLL_DIV_P_SHIFT) & PLL_DIV_P_MASK;
+	den = 1 << den;
+	den *= (val >> PLL_DIV_N_SHIFT) & PLL_DIV_N_MASK;
+
+	/* calculate numerator & denominator */
+	if (!mode) {
+		/* Normal mode */
+		num *= (val >> PLL_NORM_FDBK_M_SHIFT) & PLL_NORM_FDBK_M_MASK;
+	} else {
+		/* Dithered mode */
+		num *= (val >> PLL_DITH_FDBK_M_SHIFT) & PLL_DITH_FDBK_M_MASK;
+		den *= 256;
+	}
+
+	clk->rate = (((clk->pclk->rate/10000) * num) / den) * 10000;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+
+/* calculates current programmed rate of ahb or apb bus */
+void bus_clk_recalc(struct clk *clk)
+{
+	struct bus_clk_config *config = clk->private_data;
+	unsigned int div;
+	unsigned long flags;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	div = ((readl(config->reg) >> config->shift) & config->mask) + 1;
+	clk->rate = (unsigned long)clk->pclk->rate / div;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+
+/*
+ * calculates current programmed rate of auxiliary synthesizers
+ * used by: UART, FIRDA
+ *
+ * Fout from synthesizer can be given from two equations:
+ * Fout1 = (Fin * X/Y)/2
+ * Fout2 = Fin * X/Y
+ *
+ * Selection of eqn 1 or 2 is programmed in register
+ */
+void aux_clk_recalc(struct clk *clk)
+{
+	struct aux_clk_config *config = clk->private_data;
+	struct pclk_info *pclk_info = NULL;
+	unsigned int num = 1, den = 1, val, eqn;
+	unsigned long flags;
+
+	/* get current programmed parent */
+	pclk_info = pclk_info_get(clk);
+	if (!pclk_info) {
+		spin_lock_irqsave(&clocks_lock, flags);
+		clk->pclk = NULL;
+		clk->rate = 0;
+		spin_unlock_irqrestore(&clocks_lock, flags);
+		return;
+	}
+
+	change_parent(clk, pclk_info->pclk);
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	if (pclk_info->scalable) {
+		val = readl(config->synth_reg);
+
+		eqn = (val >> AUX_EQ_SEL_SHIFT) & AUX_EQ_SEL_MASK;
+		if (eqn == AUX_EQ1_SEL)
+			den *= 2;
+
+		/* calculate numerator */
+		num = (val >> AUX_XSCALE_SHIFT) & AUX_XSCALE_MASK;
+
+		/* calculate denominator */
+		den *= (val >> AUX_YSCALE_SHIFT) & AUX_YSCALE_MASK;
+		val = (((clk->pclk->rate/10000) * num) / den) * 10000;
+	} else
+		val = clk->pclk->rate;
+
+	clk->rate = val;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+
+/*
+ * calculates current programmed rate of gpt synthesizers
+ * Fout from synthesizer can be given from below equations:
+ * Fout= Fin/((2 ^ (N+1)) * (M+1))
+ */
+void gpt_clk_recalc(struct clk *clk)
+{
+	struct aux_clk_config *config = clk->private_data;
+	struct pclk_info *pclk_info = NULL;
+	unsigned int div = 1, val;
+	unsigned long flags;
+
+	pclk_info = pclk_info_get(clk);
+	if (!pclk_info) {
+		spin_lock_irqsave(&clocks_lock, flags);
+		clk->pclk = NULL;
+		clk->rate = 0;
+		spin_unlock_irqrestore(&clocks_lock, flags);
+		return;
+	}
+
+	change_parent(clk, pclk_info->pclk);
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	if (pclk_info->scalable) {
+		val = readl(config->synth_reg);
+		div += (val >> GPT_MSCALE_SHIFT) & GPT_MSCALE_MASK;
+		div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1);
+	}
+
+	clk->rate = (unsigned long)clk->pclk->rate / div;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+
+/*
+ * Used for clocks that always have same value as the parent clock divided by a
+ * fixed divisor
+ */
+void follow_parent(struct clk *clk)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&clocks_lock, flags);
+	clk->rate = clk->pclk->rate;
+	spin_unlock_irqrestore(&clocks_lock, flags);
+}
+
+/**
+ * recalc_root_clocks - recalculate and propagate all root clocks
+ *
+ * Recalculates all root clocks (clocks with no parent), which if the
+ * clock's .recalc is set correctly, should also propagate their rates.
+ */
+void recalc_root_clocks(void)
+{
+	propagate_rate(&root_clks);
+}
diff --git a/arch/arm/plat-spear/include/plat/clkdev.h b/arch/arm/plat-spear/include/plat/clkdev.h
new file mode 100644
index 000000000000..a2d0112fcaf7
--- /dev/null
+++ b/arch/arm/plat-spear/include/plat/clkdev.h
@@ -0,0 +1,20 @@
+/*
+ * arch/arm/plat-spear/include/plat/clkdev.h
+ *
+ * Clock Dev framework definitions for SPEAr platform
+ *
+ * Copyright (C) 2009 ST Microelectronics
+ * Viresh Kumar<viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __PLAT_CLKDEV_H
+#define __PLAT_CLKDEV_H
+
+#define __clk_get(clk) ({ 1; })
+#define __clk_put(clk) do { } while (0)
+
+#endif /* __PLAT_CLKDEV_H */
diff --git a/arch/arm/plat-spear/include/plat/clock.h b/arch/arm/plat-spear/include/plat/clock.h
new file mode 100644
index 000000000000..298bafc0a52f
--- /dev/null
+++ b/arch/arm/plat-spear/include/plat/clock.h
@@ -0,0 +1,126 @@
+/*
+ * arch/arm/plat-spear/include/plat/clock.h
+ *
+ * Clock framework definitions for SPEAr platform
+ *
+ * Copyright (C) 2009 ST Microelectronics
+ * Viresh Kumar<viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __PLAT_CLOCK_H
+#define __PLAT_CLOCK_H
+
+#include <linux/list.h>
+#include <asm/clkdev.h>
+#include <linux/types.h>
+
+/* clk structure flags */
+#define	ALWAYS_ENABLED		(1 << 0) /* clock always enabled */
+#define	RESET_TO_ENABLE		(1 << 1) /* reset register bit to enable clk */
+
+/**
+ * struct clkops - clock operations
+ * @enable: pointer to clock enable function
+ * @disable: pointer to clock disable function
+ */
+struct clkops {
+	int (*enable) (struct clk *);
+	void (*disable) (struct clk *);
+};
+
+/**
+ * struct pclk_info - parents info
+ * @pclk: pointer to parent clk
+ * @pclk_mask: value to be written for selecting this parent
+ * @scalable: Is parent scalable (1 - YES, 0 - NO)
+ */
+struct pclk_info {
+	struct clk *pclk;
+	u8 pclk_mask;
+	u8 scalable;
+};
+
+/**
+ * struct pclk_sel - parents selection configuration
+ * @pclk_info: pointer to array of parent clock info
+ * @pclk_count: number of parents
+ * @pclk_sel_reg: register for selecting a parent
+ * @pclk_sel_mask: mask for selecting parent (can be used to clear bits also)
+ */
+struct pclk_sel {
+	struct pclk_info *pclk_info;
+	u8 pclk_count;
+	unsigned int *pclk_sel_reg;
+	unsigned int pclk_sel_mask;
+};
+
+/**
+ * struct clk - clock structure
+ * @usage_count: num of users who enabled this clock
+ * @flags: flags for clock properties
+ * @rate: programmed clock rate in Hz
+ * @en_reg: clk enable/disable reg
+ * @en_reg_bit: clk enable/disable bit
+ * @ops: clk enable/disable ops - generic_clkops selected if NULL
+ * @recalc: pointer to clock rate recalculate function
+ * @pclk: current parent clk
+ * @pclk_sel: pointer to parent selection structure
+ * @pclk_sel_shift: register shift for selecting parent of this clock
+ * @children: list for childrens or this clock
+ * @sibling: node for list of clocks having same parents
+ * @private_data: clock specific private data
+ */
+struct clk {
+	unsigned int usage_count;
+	unsigned int flags;
+	unsigned long rate;
+	unsigned int *en_reg;
+	u8 en_reg_bit;
+	const struct clkops *ops;
+	void (*recalc) (struct clk *);
+
+	struct clk *pclk;
+	struct pclk_sel *pclk_sel;
+	unsigned int pclk_sel_shift;
+
+	struct list_head children;
+	struct list_head sibling;
+	void *private_data;
+};
+
+/* pll configuration structure */
+struct pll_clk_config {
+	unsigned int *mode_reg;
+	unsigned int *cfg_reg;
+};
+
+/* ahb and apb bus configuration structure */
+struct bus_clk_config {
+	unsigned int *reg;
+	unsigned int mask;
+	unsigned int shift;
+};
+
+/*
+ * Aux clk configuration structure: applicable to GPT, UART and FIRDA
+ */
+struct aux_clk_config {
+	unsigned int *synth_reg;
+};
+
+/* platform specific clock functions */
+void clk_register(struct clk_lookup *cl);
+void recalc_root_clocks(void);
+
+/* clock recalc functions */
+void follow_parent(struct clk *clk);
+void pll1_clk_recalc(struct clk *clk);
+void bus_clk_recalc(struct clk *clk);
+void gpt_clk_recalc(struct clk *clk);
+void aux_clk_recalc(struct clk *clk);
+
+#endif /* __PLAT_CLOCK_H */