--- /dev/null
+/*
+ * 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;
+ unsigned 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);
--- /dev/null
+/*
+ * TI DaVinci AEMIF support
+ *
+ * Copyright 2010 (C) Texas Instruments, Inc. http://www.ti.com/
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+#ifndef _MACH_DAVINCI_AEMIF_H
+#define _MACH_DAVINCI_AEMIF_H
+
+#define NRCSR_OFFSET 0x00
+#define AWCCR_OFFSET 0x04
+#define A1CR_OFFSET 0x10
+
+#define ACR_ASIZE_MASK 0x3
+#define ACR_EW_MASK BIT(30)
+#define ACR_SS_MASK BIT(31)
+
+/* All timings in nanoseconds */
+struct davinci_aemif_timing {
+ u8 wsetup;
+ u8 wstrobe;
+ u8 whold;
+
+ u8 rsetup;
+ u8 rstrobe;
+ u8 rhold;
+
+ u8 ta;
+};
+
+int davinci_aemif_setup_timing(struct davinci_aemif_timing *t,
+ void __iomem *base, unsigned cs);
+#endif
projects / karo-tx-linux.git / commitdiff