arm920t/at91: add clock.c

This patch adds an copy of arm926ejs/at91/clock.c to arm920t/at91. The
arm926ejs specialities are removed from arm920t version and vice versa.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>

2 files changed, 161 insertions, 0 deletions

diff --git a/arch/arm/cpu/arm920t/at91/Makefile b/arch/arm/cpu/arm920t/at91/Makefile
index 5c71b77747..8258ecd664 100644
--- a/arch/arm/cpu/arm920t/at91/Makefile
+++ b/arch/arm/cpu/arm920t/at91/Makefile
@@ -28,6 +28,7 @@ LIB	= $(obj)lib$(SOC).o
 SOBJS	+= lowlevel_init.o
 COBJS	+= reset.o
 COBJS	+= timer.o
+COBJS	+= clock.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))
diff --git a/arch/arm/cpu/arm920t/at91/clock.c b/arch/arm/cpu/arm920t/at91/clock.c
new file mode 100644
index 0000000000..02318b33f5
--- /dev/null
+++ b/arch/arm/cpu/arm920t/at91/clock.c
@@ -0,0 +1,160 @@
+/*
+ * [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
+ *
+ * Copyright (C) 2011 Andreas Bießmann
+ * 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 <common.h>
+#include <asm/io.h>
+#include <asm/arch/hardware.h>
+#include <asm/arch/at91_pmc.h>
+#include <asm/arch/clk.h>
+
+#if !defined(CONFIG_AT91FAMILY)
+# error You need to define CONFIG_AT91FAMILY in your board config!
+#endif
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static unsigned long at91_css_to_rate(unsigned long css)
+{
+	switch (css) {
+	case AT91_PMC_MCKR_CSS_SLOW:
+		return CONFIG_SYS_AT91_SLOW_CLOCK;
+	case AT91_PMC_MCKR_CSS_MAIN:
+		return gd->main_clk_rate_hz;
+	case AT91_PMC_MCKR_CSS_PLLA:
+		return gd->plla_rate_hz;
+	case AT91_PMC_MCKR_CSS_PLLB:
+		return gd->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 (input < 100000)
+			continue;
+		if (input > 32000000)
+			continue;
+
+		mul1 = out_freq / input;
+		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;
+}
+#endif
+
+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;
+}
+
+
+int at91_clock_init(unsigned long main_clock)
+{
+	unsigned freq, mckr;
+	at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC;
+#ifndef CONFIG_SYS_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 = readl(&pmc->mcfr);
+		} while (!(tmp & AT91_PMC_MCFR_MAINRDY));
+		tmp &= AT91_PMC_MCFR_MAINF_MASK;
+		main_clock = tmp * (CONFIG_SYS_AT91_SLOW_CLOCK / 16);
+	}
+#endif
+	gd->main_clk_rate_hz = main_clock;
+
+	/* report if PLLA is more than mildly overclocked */
+	gd->plla_rate_hz = at91_pll_rate(main_clock, readl(&pmc->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!
+	 */
+	gd->at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
+			     AT91_PMC_PLLBR_USBDIV_2;
+	gd->pllb_rate_hz = at91_pll_rate(main_clock, gd->at91_pllb_usb_init);
+#endif
+
+	/*
+	 * MCK and CPU derive from one of those primary clocks.
+	 * For now, assume this parentage won't change.
+	 */
+	mckr = readl(&pmc->mckr);
+	gd->mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
+	freq = gd->mck_rate_hz;
+
+	freq /= (1 << ((mckr & AT91_PMC_MCKR_PRES_MASK) >> 2));	/* prescale */
+	/* mdiv */
+	gd->mck_rate_hz = freq / (1 + ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
+	gd->cpu_clk_rate_hz = freq;
+
+	return 0;
+}
+