[PATCH 20/47] davinci: add support for aemif timing configuration
Kevin Hilman
khilman at deeprootsystems.com
Fri Oct 1 17:29:44 EDT 2010
From: Sekhar Nori <nsekhar at ti.com>
This patch adds support to configure the AEMIF interface
with supplied timing values.
Since this capability is useful both from NOR and NAND
flashes, it is provided as a new interface and in a file
of its own.
AEMIF timing configuration is required in cases:
1) Where the AEMIF clock rate can change at runtime (a side
affect of cpu frequency change).
2) Where U-Boot does not support NAND/NOR but supports other
media like SPI Flash or MMC/SD and thus does not care about
setting up the AEMIF timing for kernel to use.
3) Where U-Boot just hasn't configured the timing values and
cannot be upgraded because the box is already in the field.
Since there is now a header file for AEMIF interface, the
common (non-NAND specific) defines for AEMIF registers have
been moved from nand.h into the newly created aemif.h
Signed-off-by: Sekhar Nori <nsekhar at ti.com>
Acked-by: Kevin Hilman <khilman at deeprootsystems.com>
Signed-off-by: Kevin Hilman <khilman at deeprootsystems.com>
---
arch/arm/mach-davinci/Makefile | 2 +-
arch/arm/mach-davinci/aemif.c | 133 ++++++++++++++++++++++++++++
arch/arm/mach-davinci/include/mach/aemif.h | 36 ++++++++
arch/arm/mach-davinci/include/mach/nand.h | 3 -
drivers/mtd/nand/davinci_nand.c | 1 +
5 files changed, 171 insertions(+), 4 deletions(-)
create mode 100644 arch/arm/mach-davinci/aemif.c
create mode 100644 arch/arm/mach-davinci/include/mach/aemif.h
diff --git a/arch/arm/mach-davinci/Makefile b/arch/arm/mach-davinci/Makefile
index eab4c0f..77a0f71 100644
--- a/arch/arm/mach-davinci/Makefile
+++ b/arch/arm/mach-davinci/Makefile
@@ -5,7 +5,7 @@
# Common objects
obj-y := time.o clock.o serial.o io.o psc.o \
- gpio.o dma.o usb.o common.o sram.o
+ gpio.o dma.o usb.o common.o sram.o aemif.o
obj-$(CONFIG_DAVINCI_MUX) += mux.o
diff --git a/arch/arm/mach-davinci/aemif.c b/arch/arm/mach-davinci/aemif.c
new file mode 100644
index 0000000..9c3f500
--- /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;
+ 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);
diff --git a/arch/arm/mach-davinci/include/mach/aemif.h b/arch/arm/mach-davinci/include/mach/aemif.h
new file mode 100644
index 0000000..05b2934
--- /dev/null
+++ b/arch/arm/mach-davinci/include/mach/aemif.h
@@ -0,0 +1,36 @@
+/*
+ * 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
diff --git a/arch/arm/mach-davinci/include/mach/nand.h b/arch/arm/mach-davinci/include/mach/nand.h
index b2ad809..b5893f0 100644
--- a/arch/arm/mach-davinci/include/mach/nand.h
+++ b/arch/arm/mach-davinci/include/mach/nand.h
@@ -30,9 +30,6 @@
#include <linux/mtd/nand.h>
-#define NRCSR_OFFSET 0x00
-#define AWCCR_OFFSET 0x04
-#define A1CR_OFFSET 0x10
#define NANDFCR_OFFSET 0x60
#define NANDFSR_OFFSET 0x64
#define NANDF1ECC_OFFSET 0x70
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 2ac7367..8e2d56c 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -35,6 +35,7 @@
#include <linux/slab.h>
#include <mach/nand.h>
+#include <mach/aemif.h>
#include <asm/mach-types.h>
--
1.7.2.1
More information about the linux-arm-kernel
mailing list