at91sam9/at91cap: improve clock framework

calculate dynamically the clock rate and pllb setting for usb

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

1 files changed, 202 insertions, 0 deletions

diff --git a/cpu/arm926ejs/at91/clock.c b/cpu/arm926ejs/at91/clock.c
new file mode 100644
index 0000000000..31e53b30dd
--- /dev/null
+++ b/cpu/arm926ejs/at91/clock.c
@@ -0,0 +1,202 @@
+/*
+ * [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
+ *
+ * Copyright (C) 2005 David Brownell
+ * Copyright (C) 2005 Ivan Kokshaysky
+ * Copyright (C) 2009 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
+ *
+ * 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 <config.h>
+#include <asm/arch/hardware.h>
+#include <asm/arch/at91_pmc.h>
+#include <asm/arch/clk.h>
+#include <asm/arch/io.h>
+
+static unsigned long cpu_clk_rate_hz;
+static unsigned long main_clk_rate_hz;
+static unsigned long mck_rate_hz;
+static unsigned long plla_rate_hz;
+static unsigned long pllb_rate_hz;
+static u32 at91_pllb_usb_init;
+
+unsigned long get_cpu_clk_rate(void)
+{
+	return cpu_clk_rate_hz;
+}
+
+unsigned long get_main_clk_rate(void)
+{
+	return main_clk_rate_hz;
+}
+
+unsigned long get_mck_clk_rate(void)
+{
+	return mck_rate_hz;
+}
+
+unsigned long get_plla_clk_rate(void)
+{
+	return plla_rate_hz;
+}
+
+unsigned long get_pllb_clk_rate(void)
+{
+	return pllb_rate_hz;
+}
+
+u32 get_pllb_init(void)
+{
+	return at91_pllb_usb_init;
+}
+
+static unsigned long at91_css_to_rate(unsigned long css)
+{
+	switch (css) {
+		case AT91_PMC_CSS_SLOW:
+			return AT91_SLOW_CLOCK;
+		case AT91_PMC_CSS_MAIN:
+			return main_clk_rate_hz;
+		case AT91_PMC_CSS_PLLA:
+			return plla_rate_hz;
+		case AT91_PMC_CSS_PLLB:
+			return pllb_rate_hz;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_USB_ATMEL
+static unsigned at91_pll_calc(unsigned main_freq, unsigned out_freq)
+{
+	unsigned i, div = 0, mul = 0, diff = 1 << 30;
+	unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
+
+	/* PLL output max 240 MHz (or 180 MHz per errata) */
+	if (out_freq > 240000000)
+		goto fail;
+
+	for (i = 1; i < 256; i++) {
+		int diff1;
+		unsigned input, mul1;
+
+		/*
+		 * PLL input between 1MHz and 32MHz per spec, but lower
+		 * frequences seem necessary in some cases so allow 100K.
+		 * Warning: some newer products need 2MHz min.
+		 */
+		input = main_freq / i;
+#if defined(CONFIG_AT91SAM9G20)
+		if (input < 2000000)
+			continue;
+#endif
+		if (input < 100000)
+			continue;
+		if (input > 32000000)
+			continue;
+
+		mul1 = out_freq / input;
+#if defined(CONFIG_AT91SAM9G20)
+		if (mul > 63)
+			continue;
+#endif
+		if (mul1 > 2048)
+			continue;
+		if (mul1 < 2)
+			goto fail;
+
+		diff1 = out_freq - input * mul1;
+		if (diff1 < 0)
+			diff1 = -diff1;
+		if (diff > diff1) {
+			diff = diff1;
+			div = i;
+			mul = mul1;
+			if (diff == 0)
+				break;
+		}
+	}
+	if (i == 256 && diff > (out_freq >> 5))
+		goto fail;
+	return ret | ((mul - 1) << 16) | div;
+fail:
+	return 0;
+}
+
+static u32 at91_pll_rate(u32 freq, u32 reg)
+{
+	unsigned mul, div;
+
+	div = reg & 0xff;
+	mul = (reg >> 16) & 0x7ff;
+	if (div && mul) {
+		freq /= div;
+		freq *= mul + 1;
+	} else
+		freq = 0;
+
+	return freq;
+}
+#endif
+
+int at91_clock_init(unsigned long main_clock)
+{
+	unsigned freq, mckr;
+#ifndef AT91_MAIN_CLOCK
+	unsigned tmp;
+	/*
+	 * When the bootloader initialized the main oscillator correctly,
+	 * there's no problem using the cycle counter.  But if it didn't,
+	 * or when using oscillator bypass mode, we must be told the speed
+	 * of the main clock.
+	 */
+	if (!main_clock) {
+		do {
+			tmp = at91_sys_read(AT91_CKGR_MCFR);
+		} while (!(tmp & AT91_PMC_MAINRDY));
+		main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
+	}
+#endif
+	main_clk_rate_hz = main_clock;
+
+	/* report if PLLA is more than mildly overclocked */
+	plla_rate_hz = at91_pll_rate(main_clock, at91_sys_read(AT91_CKGR_PLLAR));
+
+#ifdef CONFIG_USB_ATMEL
+	/*
+	 * USB clock init:  choose 48 MHz PLLB value,
+	 * disable 48MHz clock during usb peripheral suspend.
+	 *
+	 * REVISIT:  assumes MCK doesn't derive from PLLB!
+	 */
+	at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
+			     AT91_PMC_USB96M;
+	pllb_rate_hz = at91_pll_rate(main_clock, at91_pllb_usb_init);
+#endif
+
+	/*
+	 * MCK and CPU derive from one of those primary clocks.
+	 * For now, assume this parentage won't change.
+	 */
+	mckr = at91_sys_read(AT91_PMC_MCKR);
+	freq = mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_CSS);
+	freq /= (1 << ((mckr & AT91_PMC_PRES) >> 2));			/* prescale */
+#if defined(CONFIG_AT91RM9200)
+	mck_rate_hz = freq / (1 + ((mckr & AT91_PMC_MDIV) >> 8));	/* mdiv */
+#elif defined(CONFIG_AT91SAM9G20)
+	mck_rate_hz = (mckr & AT91_PMC_MDIV) ?
+		freq / ((mckr & AT91_PMC_MDIV) >> 7) : freq;	/* mdiv ; (x >> 7) = ((x >> 8) * 2) */
+	if (mckr & AT91_PMC_PDIV)
+		freq /= 2;		/* processor clock division */
+#else
+	mck_rate_hz = freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8));	/* mdiv */
+#endif
+	cpu_clk_rate_hz = freq;
+
+		return 0;
+}
+