davinci: major rework of clock, PLL, PSC infrastructure

This is a significant rework of the low-level clock, PLL and Power
Sleep Controller (PSC) implementation for the DaVinci family.  The
primary goal is to have better modeling if the hardware clocks and
features with the aim of DVFS functionality.

Highlights:
- model PLLs and all PLL-derived clocks
- model parent/child relationships of PLLs and clocks
- convert to new clkdev layer
- view clock frequency and refcount via /proc/davinci_clocks

Special thanks to significant contributions and testing by David
Brownell.

Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

1 files changed, 228 insertions, 157 deletions

diff --git a/arch/arm/mach-davinci/clock.c b/arch/arm/mach-davinci/clock.c
index abb92b7eca0..f0baaa15a57 100644
--- a/arch/arm/mach-davinci/clock.c
+++ b/arch/arm/mach-davinci/clock.c
@@ -1,7 +1,8 @@
 /*
- * TI DaVinci clock config file
+ * Clock and PLL control for DaVinci devices
  *
- * Copyright (C) 2006 Texas Instruments.
+ * Copyright (C) 2006-2007 Texas Instruments.
+ * Copyright (C) 2008-2009 Deep Root Systems, LLC
  *
  * 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
@@ -13,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/errno.h>
+#include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/platform_device.h>
@@ -21,98 +23,50 @@
 #include <mach/hardware.h>
 
 #include <mach/psc.h>
+#include <mach/cputype.h>
 #include "clock.h"
 
-/* PLL/Reset register offsets */
-#define PLLM		0x110
-
 static LIST_HEAD(clocks);
 static DEFINE_MUTEX(clocks_mutex);
 static DEFINE_SPINLOCK(clockfw_lock);
 
-static unsigned int commonrate;
-static unsigned int armrate;
-static unsigned int fixedrate = 27000000;	/* 27 MHZ */
-
-extern void davinci_psc_config(unsigned int domain, unsigned int id, char enable);
-
-/*
- * Returns a clock. Note that we first try to use device id on the bus
- * and clock name. If this fails, we try to use clock name only.
- */
-struct clk *clk_get(struct device *dev, const char *id)
+static unsigned psc_domain(struct clk *clk)
 {
-	struct clk *p, *clk = ERR_PTR(-ENOENT);
-	int idno;
-
-	if (dev == NULL || dev->bus != &platform_bus_type)
-		idno = -1;
-	else
-		idno = to_platform_device(dev)->id;
-
-	mutex_lock(&clocks_mutex);
-
-	list_for_each_entry(p, &clocks, node) {
-		if (p->id == idno &&
-		    strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
-			clk = p;
-			goto found;
-		}
-	}
-
-	list_for_each_entry(p, &clocks, node) {
-		if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
-			clk = p;
-			break;
-		}
-	}
-
-found:
-	mutex_unlock(&clocks_mutex);
-
-	return clk;
+	return (clk->flags & PSC_DSP)
+		? DAVINCI_GPSC_DSPDOMAIN
+		: DAVINCI_GPSC_ARMDOMAIN;
 }
-EXPORT_SYMBOL(clk_get);
 
-void clk_put(struct clk *clk)
+static void __clk_enable(struct clk *clk)
 {
-	if (clk && !IS_ERR(clk))
-		module_put(clk->owner);
-}
-EXPORT_SYMBOL(clk_put);
-
-static int __clk_enable(struct clk *clk)
-{
-	if (clk->flags & ALWAYS_ENABLED)
-		return 0;
-
-	davinci_psc_config(DAVINCI_GPSC_ARMDOMAIN, clk->lpsc, 1);
-	return 0;
+	if (clk->parent)
+		__clk_enable(clk->parent);
+	if (clk->usecount++ == 0 && (clk->flags & CLK_PSC))
+		davinci_psc_config(psc_domain(clk), clk->lpsc, 1);
 }
 
 static void __clk_disable(struct clk *clk)
 {
-	if (clk->usecount)
+	if (WARN_ON(clk->usecount == 0))
 		return;
-
-	davinci_psc_config(DAVINCI_GPSC_ARMDOMAIN, clk->lpsc, 0);
+	if (--clk->usecount == 0 && !(clk->flags & CLK_PLL))
+		davinci_psc_config(psc_domain(clk), clk->lpsc, 0);
+	if (clk->parent)
+		__clk_disable(clk->parent);
 }
 
 int clk_enable(struct clk *clk)
 {
 	unsigned long flags;
-	int ret = 0;
 
 	if (clk == NULL || IS_ERR(clk))
 		return -EINVAL;
 
-	if (clk->usecount++ == 0) {
-		spin_lock_irqsave(&clockfw_lock, flags);
-		ret = __clk_enable(clk);
-		spin_unlock_irqrestore(&clockfw_lock, flags);
-	}
+	spin_lock_irqsave(&clockfw_lock, flags);
+	__clk_enable(clk);
+	spin_unlock_irqrestore(&clockfw_lock, flags);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(clk_enable);
 
@@ -123,11 +77,9 @@ void clk_disable(struct clk *clk)
 	if (clk == NULL || IS_ERR(clk))
 		return;
 
-	if (clk->usecount > 0 && !(--clk->usecount)) {
-		spin_lock_irqsave(&clockfw_lock, flags);
-		__clk_disable(clk);
-		spin_unlock_irqrestore(&clockfw_lock, flags);
-	}
+	spin_lock_irqsave(&clockfw_lock, flags);
+	__clk_disable(clk);
+	spin_unlock_irqrestore(&clockfw_lock, flags);
 }
 EXPORT_SYMBOL(clk_disable);
 
@@ -136,7 +88,7 @@ unsigned long clk_get_rate(struct clk *clk)
 	if (clk == NULL || IS_ERR(clk))
 		return -EINVAL;
 
-	return *(clk->rate);
+	return clk->rate;
 }
 EXPORT_SYMBOL(clk_get_rate);
 
@@ -145,7 +97,7 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
 	if (clk == NULL || IS_ERR(clk))
 		return -EINVAL;
 
-	return *(clk->rate);
+	return clk->rate;
 }
 EXPORT_SYMBOL(clk_round_rate);
 
@@ -164,10 +116,23 @@ int clk_register(struct clk *clk)
 	if (clk == NULL || IS_ERR(clk))
 		return -EINVAL;
 
+	if (WARN(clk->parent && !clk->parent->rate,
+			"CLK: %s parent %s has no rate!\n",
+			clk->name, clk->parent->name))
+		return -EINVAL;
+
 	mutex_lock(&clocks_mutex);
-	list_add(&clk->node, &clocks);
+	list_add_tail(&clk->node, &clocks);
 	mutex_unlock(&clocks_mutex);
 
+	/* If rate is already set, use it */
+	if (clk->rate)
+		return 0;
+
+	/* Otherwise, default to parent rate */
+	if (clk->parent)
+		clk->rate = clk->parent->rate;
+
 	return 0;
 }
 EXPORT_SYMBOL(clk_register);
@@ -183,84 +148,150 @@ void clk_unregister(struct clk *clk)
 }
 EXPORT_SYMBOL(clk_unregister);
 
-static struct clk davinci_clks[] = {
-	{
-		.name = "ARMCLK",
-		.rate = &armrate,
-		.lpsc = -1,
-		.flags = ALWAYS_ENABLED,
-	},
-	{
-		.name = "UART",
-		.rate = &fixedrate,
-		.lpsc = DAVINCI_LPSC_UART0,
-	},
-	{
-		.name = "EMACCLK",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_EMAC_WRAPPER,
-	},
-	{
-		.name = "I2CCLK",
-		.rate = &fixedrate,
-		.lpsc = DAVINCI_LPSC_I2C,
-	},
-	{
-		.name = "IDECLK",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_ATA,
-	},
-	{
-		.name = "McBSPCLK",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_McBSP,
-	},
-	{
-		.name = "MMCSDCLK",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_MMC_SD,
-	},
-	{
-		.name = "SPICLK",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_SPI,
-	},
-	{
-		.name = "gpio",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_GPIO,
-	},
-	{
-		.name = "usb",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_USB,
-	},
-	{
-		.name = "AEMIFCLK",
-		.rate = &commonrate,
-		.lpsc = DAVINCI_LPSC_AEMIF,
-		.usecount = 1,
+#ifdef CONFIG_DAVINCI_RESET_CLOCKS
+/*
+ * Disable any unused clocks left on by the bootloader
+ */
+static int __init clk_disable_unused(void)
+{
+	struct clk *ck;
+
+	spin_lock_irq(&clockfw_lock);
+	list_for_each_entry(ck, &clocks, node) {
+		if (ck->usecount > 0)
+			continue;
+		if (!(ck->flags & CLK_PSC))
+			continue;
+
+		/* ignore if in Disabled or SwRstDisable states */
+		if (!davinci_psc_is_clk_active(ck->lpsc))
+			continue;
+
+		pr_info("Clocks: disable unused %s\n", ck->name);
+		davinci_psc_config(psc_domain(ck), ck->lpsc, 0);
 	}
-};
+	spin_unlock_irq(&clockfw_lock);
+
+	return 0;
+}
+late_initcall(clk_disable_unused);
+#endif
 
-int __init davinci_clk_init(void)
+static void clk_sysclk_recalc(struct clk *clk)
 {
-	struct clk *clkp;
-	int count = 0;
-	u32 pll_mult;
-
-	pll_mult = davinci_readl(DAVINCI_PLL_CNTRL0_BASE + PLLM);
-	commonrate = ((pll_mult + 1) * 27000000) / 6;
-	armrate = ((pll_mult + 1) * 27000000) / 2;
-
-	for (clkp = davinci_clks; count < ARRAY_SIZE(davinci_clks);
-	     count++, clkp++) {
-		clk_register(clkp);
-
-		/* Turn on clocks that have been enabled in the
-		 * table above */
-		if (clkp->usecount)
-			clk_enable(clkp);
+	u32 v, plldiv;
+	struct pll_data *pll;
+
+	/* If this is the PLL base clock, no more calculations needed */
+	if (clk->pll_data)
+		return;
+
+	if (WARN_ON(!clk->parent))
+		return;
+
+	clk->rate = clk->parent->rate;
+
+	/* Otherwise, the parent must be a PLL */
+	if (WARN_ON(!clk->parent->pll_data))
+		return;
+
+	pll = clk->parent->pll_data;
+
+	/* If pre-PLL, source clock is before the multiplier and divider(s) */
+	if (clk->flags & PRE_PLL)
+		clk->rate = pll->input_rate;
+
+	if (!clk->div_reg)
+		return;
+
+	v = __raw_readl(pll->base + clk->div_reg);
+	if (v & PLLDIV_EN) {
+		plldiv = (v & PLLDIV_RATIO_MASK) + 1;
+		if (plldiv)
+			clk->rate /= plldiv;
+	}
+}
+
+static void __init clk_pll_init(struct clk *clk)
+{
+	u32 ctrl, mult = 1, prediv = 1, postdiv = 1;
+	u8 bypass;
+	struct pll_data *pll = clk->pll_data;
+
+	pll->base = IO_ADDRESS(pll->phys_base);
+	ctrl = __raw_readl(pll->base + PLLCTL);
+	clk->rate = pll->input_rate = clk->parent->rate;
+
+	if (ctrl & PLLCTL_PLLEN) {
+		bypass = 0;
+		mult = __raw_readl(pll->base + PLLM);
+		mult = (mult & PLLM_PLLM_MASK) + 1;
+	} else
+		bypass = 1;
+
+	if (pll->flags & PLL_HAS_PREDIV) {
+		prediv = __raw_readl(pll->base + PREDIV);
+		if (prediv & PLLDIV_EN)
+			prediv = (prediv & PLLDIV_RATIO_MASK) + 1;
+		else
+			prediv = 1;
+	}
+
+	/* pre-divider is fixed, but (some?) chips won't report that */
+	if (cpu_is_davinci_dm355() && pll->num == 1)
+		prediv = 8;
+
+	if (pll->flags & PLL_HAS_POSTDIV) {
+		postdiv = __raw_readl(pll->base + POSTDIV);
+		if (postdiv & PLLDIV_EN)
+			postdiv = (postdiv & PLLDIV_RATIO_MASK) + 1;
+		else
+			postdiv = 1;
+	}
+
+	if (!bypass) {
+		clk->rate /= prediv;
+		clk->rate *= mult;
+		clk->rate /= postdiv;
+	}
+
+	pr_debug("PLL%d: input = %lu MHz [ ",
+		 pll->num, clk->parent->rate / 1000000);
+	if (bypass)
+		pr_debug("bypass ");
+	if (prediv > 1)
+		pr_debug("/ %d ", prediv);
+	if (mult > 1)
+		pr_debug("* %d ", mult);
+	if (postdiv > 1)
+		pr_debug("/ %d ", postdiv);
+	pr_debug("] --> %lu MHz output.\n", clk->rate / 1000000);
+}
+
+int __init davinci_clk_init(struct davinci_clk *clocks)
+  {
+	struct davinci_clk *c;
+	struct clk *clk;
+
+	for (c = clocks; c->lk.clk; c++) {
+		clk = c->lk.clk;
+
+		if (clk->pll_data)
+			clk_pll_init(clk);
+
+		/* Calculate rates for PLL-derived clocks */
+		else if (clk->flags & CLK_PLL)
+			clk_sysclk_recalc(clk);
+
+		if (clk->lpsc)
+			clk->flags |= CLK_PSC;
+
+		clkdev_add(&c->lk);
+		clk_register(clk);
+
+		/* Turn on clocks that Linux doesn't otherwise manage */
+		if (clk->flags & ALWAYS_ENABLED)
+			clk_enable(clk);
 	}
 
 	return 0;
@@ -285,12 +316,52 @@ static void davinci_ck_stop(struct seq_file *m, void *v)
 {
 }
 
-static int davinci_ck_show(struct seq_file *m, void *v)
+#define CLKNAME_MAX	10		/* longest clock name */
+#define NEST_DELTA	2
+#define NEST_MAX	4
+
+static void
+dump_clock(struct seq_file *s, unsigned nest, struct clk *parent)
 {
-	struct clk *cp;
+	char		*state;
+	char		buf[CLKNAME_MAX + NEST_DELTA * NEST_MAX];
+	struct clk	*clk;
+	unsigned	i;
+
+	if (parent->flags & CLK_PLL)
+		state = "pll";
+	else if (parent->flags & CLK_PSC)
+		state = "psc";
+	else
+		state = "";
+
+	/* <nest spaces> name <pad to end> */
+	memset(buf, ' ', sizeof(buf) - 1);
+	buf[sizeof(buf) - 1] = 0;
+	i = strlen(parent->name);
+	memcpy(buf + nest, parent->name,
+			min(i, (unsigned)(sizeof(buf) - 1 - nest)));
+
+	seq_printf(s, "%s users=%2d %-3s %9ld Hz\n",
+		   buf, parent->usecount, state, clk_get_rate(parent));
+	/* REVISIT show device associations too */
+
+	/* cost is now small, but not linear... */
+	list_for_each_entry(clk, &clocks, node) {
+		if (clk->parent == parent)
+			dump_clock(s, nest + NEST_DELTA, clk);
+	}
+}
 
-	list_for_each_entry(cp, &clocks, node)
-		seq_printf(m,"%s %d %d\n", cp->name, *(cp->rate), cp->usecount);
+static int davinci_ck_show(struct seq_file *m, void *v)
+{
+	/* Show clock tree; we know the main oscillator is first.
+	 * We trust nonzero usecounts equate to PSC enables...
+	 */
+	mutex_lock(&clocks_mutex);
+	if (!list_empty(&clocks))
+		dump_clock(m, 0, list_first_entry(&clocks, struct clk, node));
+	mutex_unlock(&clocks_mutex);
 
 	return 0;
 }
@@ -321,4 +392,4 @@ static int __init davinci_ck_proc_init(void)
 
 }
 __initcall(davinci_ck_proc_init);
-#endif	/* CONFIG_DEBUG_PROC_FS */
+#endif /* CONFIG_DEBUG_PROC_FS */