Merge branch 'master' into tk71

[mv-sheeva.git] / arch / arm / mach-davinci / aemif.c

diff --git a/arch/arm/mach-davinci/aemif.c b/arch/arm/mach-davinci/aemif.c
new file mode 100644 (file)
index 0000000..1ce70a9
--- /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);