[ARM] 3634/1: ep93xx: initial implementation of the clk_* API

Patch from Lennert Buytenhek

Add an initial implementation of the clk_* API for the cirrus ep93xx
to the tree.  The initial implementation is somewhat minimal, with the
intention of extending it as we go along.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-ep93xx/Makefile

@@ -1,7 +1,7 @@
 #
 # Makefile for the linux kernel.
 #
-obj-y			:= core.o
+obj-y			:= core.o clock.o
 obj-m			:=
 obj-n			:=
 obj-			:=

arch/arm/mach-ep93xx/clock.c

@@ -0,0 +1,156 @@
+/*
+ * arch/arm/mach-ep93xx/clock.c
+ * Clock control for Cirrus EP93xx chips.
+ *
+ * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
+ *
+ * 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
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <asm/div64.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+
+struct clk {
+	char		*name;
+	unsigned long	rate;
+	int		users;
+	u32		enable_reg;
+	u32		enable_mask;
+};
+
+static struct clk clk_pll1 = {
+	.name		= "pll1",
+};
+static struct clk clk_f = {
+	.name		= "fclk",
+};
+static struct clk clk_h = {
+	.name		= "hclk",
+};
+static struct clk clk_p = {
+	.name		= "pclk",
+};
+static struct clk clk_pll2 = {
+	.name		= "pll2",
+};
+static struct clk clk_usb_host = {
+	.name		= "usb_host",
+	.enable_reg	= EP93XX_SYSCON_CLOCK_CONTROL,
+	.enable_mask	= EP93XX_SYSCON_CLOCK_USH_EN,
+};
+
+
+static struct clk *clocks[] = {
+	&clk_pll1,
+	&clk_f,
+	&clk_h,
+	&clk_p,
+	&clk_pll2,
+	&clk_usb_host,
+};
+
+struct clk *clk_get(struct device *dev, const char *id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(clocks); i++) {
+		if (!strcmp(clocks[i]->name, id))
+			return clocks[i];
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+int clk_enable(struct clk *clk)
+{
+	if (!clk->users++ && clk->enable_reg) {
+		u32 value;
+
+		value = __raw_readl(clk->enable_reg);
+		__raw_writel(value | clk->enable_mask, clk->enable_reg);
+	}
+
+	return 0;
+}
+
+void clk_disable(struct clk *clk)
+{
+	if (!--clk->users && clk->enable_reg) {
+		u32 value;
+
+		value = __raw_readl(clk->enable_reg);
+		__raw_writel(value & ~clk->enable_mask, clk->enable_reg);
+	}
+}
+
+unsigned long clk_get_rate(struct clk *clk)
+{
+	return clk->rate;
+}
+
+void clk_put(struct clk *clk)
+{
+}
+
+
+
+static char fclk_divisors[] = { 1, 2, 4, 8, 16, 1, 1, 1 };
+static char hclk_divisors[] = { 1, 2, 4, 5, 6, 8, 16, 32 };
+static char pclk_divisors[] = { 1, 2, 4, 8 };
+
+/*
+ * PLL rate = 14.7456 MHz * (X1FBD + 1) * (X2FBD + 1) / (X2IPD + 1) / 2^PS
+ */
+static unsigned long calc_pll_rate(u32 config_word)
+{
+	unsigned long long rate;
+	int i;
+
+	rate = 14745600;
+	rate *= ((config_word >> 11) & 0x1f) + 1;		/* X1FBD */
+	rate *= ((config_word >> 5) & 0x3f) + 1;		/* X2FBD */
+	do_div(rate, (config_word & 0x1f) + 1);			/* X2IPD */
+	for (i = 0; i < ((config_word >> 16) & 3); i++)		/* PS */
+		rate >>= 1;
+
+	return (unsigned long)rate;
+}
+
+void ep93xx_clock_init(void)
+{
+	u32 value;
+
+	value = __raw_readl(EP93XX_SYSCON_CLOCK_SET1);
+	if (!(value & 0x00800000)) {			/* PLL1 bypassed?  */
+		clk_pll1.rate = 14745600;
+	} else {
+		clk_pll1.rate = calc_pll_rate(value);
+	}
+	clk_f.rate = clk_pll1.rate / fclk_divisors[(value >> 25) & 0x7];
+	clk_h.rate = clk_pll1.rate / hclk_divisors[(value >> 20) & 0x7];
+	clk_p.rate = clk_h.rate / pclk_divisors[(value >> 18) & 0x3];
+
+	value = __raw_readl(EP93XX_SYSCON_CLOCK_SET2);
+	if (!(value & 0x00080000)) {			/* PLL2 bypassed?  */
+		clk_pll2.rate = 14745600;
+	} else if (value & 0x00040000) {		/* PLL2 enabled?  */
+		clk_pll2.rate = calc_pll_rate(value);
+	} else {
+		clk_pll2.rate = 0;
+	}
+	clk_usb_host.rate = clk_pll2.rate / (((value >> 28) & 0xf) + 1);
+
+	printk(KERN_INFO "ep93xx: PLL1 running at %ld MHz, PLL2 at %ld MHz\n",
+		clk_pll1.rate / 1000000, clk_pll2.rate / 1000000);
+	printk(KERN_INFO "ep93xx: FCLK %ld MHz, HCLK %ld MHz, PCLK %ld MHz\n",
+		clk_f.rate / 1000000, clk_h.rate / 1000000,
+		clk_p.rate / 1000000);
+}

arch/arm/mach-ep93xx/core.c

@@ -437,6 +437,8 @@ void __init ep93xx_init_devices(void)
 {
 	unsigned int v;
 
+	ep93xx_clock_init();
+
 	/*
 	 * Disallow access to MaverickCrunch initially.
 	 */

include/asm-arm/arch-ep93xx/ep93xx-regs.h

@@ -115,6 +115,8 @@
 #define EP93XX_SYSCON_CLOCK_USH_EN	0x10000000
 #define EP93XX_SYSCON_HALT		EP93XX_SYSCON_REG(0x08)
 #define EP93XX_SYSCON_STANDBY		EP93XX_SYSCON_REG(0x0c)
+#define EP93XX_SYSCON_CLOCK_SET1	EP93XX_SYSCON_REG(0x20)
+#define EP93XX_SYSCON_CLOCK_SET2	EP93XX_SYSCON_REG(0x24)
 #define EP93XX_SYSCON_DEVICE_CONFIG	EP93XX_SYSCON_REG(0x80)
 #define EP93XX_SYSCON_DEVICE_CONFIG_CRUNCH_ENABLE	0x00800000
 #define EP93XX_SYSCON_SWLOCK		EP93XX_SYSCON_REG(0xc0)

include/asm-arm/arch-ep93xx/platform.h

@@ -8,6 +8,7 @@ void ep93xx_map_io(void);
 void ep93xx_init_irq(void);
 void ep93xx_init_time(unsigned long);
 void ep93xx_init_devices(void);
+void ep93xx_clock_init(void);
 extern struct sys_timer ep93xx_timer;