X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=arch%2Farm%2Fmach-davinci%2Faemif.c;fp=arch%2Farm%2Fmach-davinci%2Faemif.c;h=1ce70a91f2e95bc5f6f44dc5d97a85a70f5bf028;hb=f2ec334db8d14ae3ec2e4bf8d974f75b8f772e26;hp=0000000000000000000000000000000000000000;hpb=81e20d4d8d0317ecf1c7d193a52ab26cf74e1737;p=mv-sheeva.git

diff --git a/arch/arm/mach-davinci/aemif.c b/arch/arm/mach-davinci/aemif.c
new file mode 100644
index 00000000000..1ce70a91f2e
--- /dev/null
+++ b/arch/arm/mach-davinci/aemif.c
@@ -0,0 +1,133 @@
+/*
+ * AEMIF support for DaVinci SoCs
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated. http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/module.h>
+#include <linux/time.h>
+
+#include <mach/aemif.h>
+
+/* Timing value configuration */
+
+#define TA(x)		((x) << 2)
+#define RHOLD(x)	((x) << 4)
+#define RSTROBE(x)	((x) << 7)
+#define RSETUP(x)	((x) << 13)
+#define WHOLD(x)	((x) << 17)
+#define WSTROBE(x)	((x) << 20)
+#define WSETUP(x)	((x) << 26)
+
+#define TA_MAX		0x3
+#define RHOLD_MAX	0x7
+#define RSTROBE_MAX	0x3f
+#define RSETUP_MAX	0xf
+#define WHOLD_MAX	0x7
+#define WSTROBE_MAX	0x3f
+#define WSETUP_MAX	0xf
+
+#define TIMING_MASK	(TA(TA_MAX) | \
+				RHOLD(RHOLD_MAX) | \
+				RSTROBE(RSTROBE_MAX) |	\
+				RSETUP(RSETUP_MAX) | \
+				WHOLD(WHOLD_MAX) | \
+				WSTROBE(WSTROBE_MAX) | \
+				WSETUP(WSETUP_MAX))
+
+/*
+ * aemif_calc_rate - calculate timing data.
+ * @wanted: The cycle time needed in nanoseconds.
+ * @clk: The input clock rate in kHz.
+ * @max: The maximum divider value that can be programmed.
+ *
+ * On success, returns the calculated timing value minus 1 for easy
+ * programming into AEMIF timing registers, else negative errno.
+ */
+static int aemif_calc_rate(int wanted, unsigned long clk, int max)
+{
+	int result;
+
+	result = DIV_ROUND_UP((wanted * clk), NSEC_PER_MSEC) - 1;
+
+	pr_debug("%s: result %d from %ld, %d\n", __func__, result, clk, wanted);
+
+	/* It is generally OK to have a more relaxed timing than requested... */
+	if (result < 0)
+		result = 0;
+
+	/* ... But configuring tighter timings is not an option. */
+	else if (result > max)
+		result = -EINVAL;
+
+	return result;
+}
+
+/**
+ * davinci_aemif_setup_timing - setup timing values for a given AEMIF interface
+ * @t: timing values to be progammed
+ * @base: The virtual base address of the AEMIF interface
+ * @cs: chip-select to program the timing values for
+ *
+ * This function programs the given timing values (in real clock) into the
+ * AEMIF registers taking the AEMIF clock into account.
+ *
+ * This function does not use any locking while programming the AEMIF
+ * because it is expected that there is only one user of a given
+ * chip-select.
+ *
+ * Returns 0 on success, else negative errno.
+ */
+int davinci_aemif_setup_timing(struct davinci_aemif_timing *t,
+					void __iomem *base, unsigned cs)
+{
+	unsigned set, val;
+	int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
+	unsigned offset = A1CR_OFFSET + cs * 4;
+	struct clk *aemif_clk;
+	unsigned long clkrate;
+
+	if (!t)
+		return 0;	/* Nothing to do */
+
+	aemif_clk = clk_get(NULL, "aemif");
+	if (IS_ERR(aemif_clk))
+		return PTR_ERR(aemif_clk);
+
+	clkrate = clk_get_rate(aemif_clk);
+
+	clkrate /= 1000;	/* turn clock into kHz for ease of use */
+
+	ta	= aemif_calc_rate(t->ta, clkrate, TA_MAX);
+	rhold	= aemif_calc_rate(t->rhold, clkrate, RHOLD_MAX);
+	rstrobe	= aemif_calc_rate(t->rstrobe, clkrate, RSTROBE_MAX);
+	rsetup	= aemif_calc_rate(t->rsetup, clkrate, RSETUP_MAX);
+	whold	= aemif_calc_rate(t->whold, clkrate, WHOLD_MAX);
+	wstrobe	= aemif_calc_rate(t->wstrobe, clkrate, WSTROBE_MAX);
+	wsetup	= aemif_calc_rate(t->wsetup, clkrate, WSETUP_MAX);
+
+	if (ta < 0 || rhold < 0 || rstrobe < 0 || rsetup < 0 ||
+			whold < 0 || wstrobe < 0 || wsetup < 0) {
+		pr_err("%s: cannot get suitable timings\n", __func__);
+		return -EINVAL;
+	}
+
+	set = TA(ta) | RHOLD(rhold) | RSTROBE(rstrobe) | RSETUP(rsetup) |
+		WHOLD(whold) | WSTROBE(wstrobe) | WSETUP(wsetup);
+
+	val = __raw_readl(base + offset);
+	val &= ~TIMING_MASK;
+	val |= set;
+	__raw_writel(val, base + offset);
+
+	return 0;
+}
+EXPORT_SYMBOL(davinci_aemif_setup_timing);