[RFC PATCH 1/2] memory: davinci - add aemif controller platform driver

[Murali Karicheri]

This is a platform driver for asynchronous external memory interface
available on TI SoCs. This driver was previously located inside the
mach-davinci folder. As this DaVinci IP is re-used across multiple
family of devices such as c6x, keystone etc, the driver is moved to drivers.
The driver configures async bus parameters associated with a particular
chip select. For DaVinci controller driver and driver for other async
devices such as NOR flash, ASRAM etc, the bus confuguration is
done by this driver at init time. A set of APIs (set/get) provided to
update the values based on specific driver usage.

Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx>
---
 .../devicetree/bindings/arm/davinci/aemif.txt      |   62 +++
 drivers/memory/Kconfig                             |   10 +
 drivers/memory/Makefile                            |    1 +
 drivers/memory/davinci-aemif.c                     |  397 ++++++++++++++++++++
 include/linux/platform_data/davinci-aemif.h        |   47 +++
 5 files changed, 517 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/davinci/aemif.txt
 create mode 100644 drivers/memory/davinci-aemif.c
 create mode 100644 include/linux/platform_data/davinci-aemif.h

diff --git a/Documentation/devicetree/bindings/arm/davinci/aemif.txt b/Documentation/devicetree/bindings/arm/davinci/aemif.txt
new file mode 100644
index 0000000..7d70d42
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/davinci/aemif.txt
@@ -0,0 +1,62 @@
+* Texas Instruments Davinci AEMIF bus interface
+
+This file provides information for the davinci-emif chip select
+bindings.
+
+This is a sub device node inside the davinci-emif device node
+to describe a async bus for a specific chip select. For NAND,
+CFI flash device bindings described inside an aemif node,
+etc, a cs sub node is defined to associate the bus parameter
+bindings used by the device.
+
+Required properties:=
+- compatible: "ti,davinci-cs";
+- #address-cells = <1>;
+- #size-cells = <1>;
+- cs - cs used by the device (NAND, CFI flash etc. values in the range: 2-5
+
+Optional properties:-
+- asize - asynchronous data bus width (0 - 8bit, 1 - 16 bit)
+  All of the params below in nanoseconds
+
+- ta - Minimum turn around time
+- rhold - read hold width
+- rstobe - read strobe width
+- rsetup - read setup width
+- whold - write hold width
+- wstrobe - write strobe width
+- wsetup - write setup width
+- ss - enable/disable select strobe (0 - disable, 1 - enable)
+- ew - enable/disable extended wait cycles (0 - disable, 1 - enable)
+
+Example for davinci nand chip select
+
+aemif@60000000 {
+
+	compatible = "ti,davinci-aemif";
+	#address-cells = <2>;
+	#size-cells = <1>;
+
+	nand_cs:cs2@70000000 {
+		compatible = "ti,davinci-cs";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		cs = <2>;
+		asize = <1>;
+		ta = <24>;
+		rhold = <48>;
+		rstrobe = <390>;
+		rsetup = <96>;
+		whold = <48>;
+		wstrobe = <390>;
+		wsetup = <96>;
+	};
+
+	nand@2,0 {
+
+	....
+
+	};
+};
+
+
diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
index 067f311..2636a95 100644
--- a/drivers/memory/Kconfig
+++ b/drivers/memory/Kconfig
@@ -40,4 +40,14 @@ config TEGRA30_MC
 	  analysis, especially for IOMMU/SMMU(System Memory Management
 	  Unit) module.
 
+config TI_DAVINCI_AEMIF
+	bool "Texas Instruments DaVinci AEMIF driver"
+	help
+	  This driver is for the AEMIF module available in Texas Instruments
+	  SoCs. AEMIF stands for Asynchronous External Memory Interface and
+	  is intended to provide a glue-less interface to a variety of
+	  asynchronuous memory devices like ASRAM, NOR and NAND memory. A total
+	  of 256M bytes of any of these memories can be accessed at a given
+	  time via four chip selects with 64M byte access per chip select.
+
 endif
diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
index 42b3ce9..246aa61 100644
--- a/drivers/memory/Makefile
+++ b/drivers/memory/Makefile
@@ -5,3 +5,4 @@
 obj-$(CONFIG_TI_EMIF)		+= emif.o
 obj-$(CONFIG_TEGRA20_MC)	+= tegra20-mc.o
 obj-$(CONFIG_TEGRA30_MC)	+= tegra30-mc.o
+obj-$(CONFIG_TI_DAVINCI_AEMIF)	+= davinci-aemif.o
diff --git a/drivers/memory/davinci-aemif.c b/drivers/memory/davinci-aemif.c
new file mode 100644
index 0000000..6c42116
--- /dev/null
+++ b/drivers/memory/davinci-aemif.c
@@ -0,0 +1,397 @@
+/*
+ * AEMIF support for DaVinci SoCs
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated. http://www.ti.com/
+ * Copyright (C) Heiko Schocher <hs@xxxxxxx>
+ *
+ * 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/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_data/davinci-aemif.h>
+#include <linux/platform_device.h>
+#include <linux/time.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 EW(x)		((x) << 30)
+#define SS(x)		((x) << 31)
+
+#define ASIZE_MAX	0x1
+#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 EW_MAX		0x1
+#define SS_MAX		0x1
+#define NUM_CS		4
+
+#define CONFIG_MASK	(TA(TA_MAX) | \
+				RHOLD(RHOLD_MAX) | \
+				RSTROBE(RSTROBE_MAX) |	\
+				RSETUP(RSETUP_MAX) | \
+				WHOLD(WHOLD_MAX) | \
+				WSTROBE(WSTROBE_MAX) | \
+				WSETUP(WSETUP_MAX) | \
+				EW(EW_MAX) | SS(SS_MAX) | \
+				ASIZE_MAX)
+
+#define DRV_NAME "davinci-aemif"
+
+struct aemif_device {
+	struct davinci_aemif_pdata *cfg;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static struct aemif_device *aemif;
+/**
+ * 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_config_abus - configure async bus parameters given
+ * AEMIF interface
+ * @cs: chip-select to program the timing values for
+ * @data: aemif chip select configuration
+ * @base: aemif io mapped configuration base
+ *
+ * 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.
+ */
+static int davinci_aemif_config_abus(unsigned int cs,
+				void __iomem *base,
+				struct davinci_aemif_cs_data *data)
+{
+	int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
+	unsigned offset = A1CR_OFFSET + cs * 4;
+	unsigned long clkrate;
+	unsigned set, val;
+
+	if (!data)
+		return -EINVAL;
+
+	clkrate = clk_get_rate(aemif->clk);
+
+	clkrate /= 1000;	/* turn clock into kHz for ease of use */
+
+	ta	= aemif_calc_rate(data->ta, clkrate, TA_MAX);
+	rhold	= aemif_calc_rate(data->rhold, clkrate, RHOLD_MAX);
+	rstrobe	= aemif_calc_rate(data->rstrobe, clkrate, RSTROBE_MAX);
+	rsetup	= aemif_calc_rate(data->rsetup, clkrate, RSETUP_MAX);
+	whold	= aemif_calc_rate(data->whold, clkrate, WHOLD_MAX);
+	wstrobe	= aemif_calc_rate(data->wstrobe, clkrate, WSTROBE_MAX);
+	wsetup	= aemif_calc_rate(data->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);
+
+	set |= (data->asize & ACR_ASIZE_MASK);
+	if (data->enable_ew)
+		set |= ACR_EW_MASK;
+	if (data->enable_ss)
+		set |= ACR_SS_MASK;
+
+	val = readl(aemif->base + offset);
+	val &= ~CONFIG_MASK;
+	val |= set;
+	writel(val, aemif->base + offset);
+
+	return 0;
+}
+
+/**
+ * get_cs_data - helper function to get bus configuration data for a given cs
+ * @cs: chip-select, values 2-5
+ */
+static struct davinci_aemif_cs_data *get_cs_data(int cs)
+{
+	int i;
+
+	for (i = 0; i < aemif->cfg->num_cs; i++) {
+		if (cs == aemif->cfg->cs_data[i].cs)
+			break;
+	}
+
+	if (i == aemif->cfg->num_cs)
+		return NULL;
+
+	return &aemif->cfg->cs_data[i];
+}
+
+/**
+ * davinci_aemif_set_abus_params - Set bus configuration data for a given cs
+ * @cs: chip-select, values 2-5
+ * @data: ptr to a struct to hold the configuration data to be set
+ *
+ * This function is called to configure emif bus parameters for a given cs.
+ * Users call this function after calling davinci_aemif_get_abus_params()
+ * to get current parameters, modify and call this function
+ */
+int davinci_aemif_set_abus_params(unsigned int cs,
+			struct davinci_aemif_cs_data *data)
+{
+	struct davinci_aemif_cs_data *curr_cs_data;
+	int ret = -EINVAL, chip_cs;
+
+	if (data == NULL)
+		return ret;
+
+	if (aemif->base == NULL)
+		return ret;
+
+	/* translate to chip CS which starts at 2 */
+	chip_cs = cs + 2;
+
+	curr_cs_data = get_cs_data(chip_cs);
+	if (curr_cs_data) {
+		ret = davinci_aemif_config_abus(chip_cs, aemif->base, data);
+		if (!ret) {
+			*curr_cs_data = *data;
+			return 0;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(davinci_aemif_set_abus_params);
+
+/**
+ * davinci_aemif_get_abus_params - Get bus configuration data for a given cs
+ * @cs: chip-select, values 2-5
+ * returns: ptr to a struct having the current configuration data
+ */
+struct davinci_aemif_cs_data *davinci_aemif_get_abus_params(unsigned int cs)
+{
+	/* translate to chip CS which starts at 2 */
+	return get_cs_data(cs + 2);
+}
+EXPORT_SYMBOL(davinci_aemif_get_abus_params);
+
+#if defined(CONFIG_OF)
+/**
+ * dv_get_value - helper function to read a attribute valye
+ * @np: device node ptr
+ * @name: name of the attribute
+ * returns: value of the attribute
+ */
+static int dv_get_value(struct device_node *np, const char *name)
+{
+	u32 data;
+	int ret;
+
+	ret = of_property_read_u32(np, name, &data);
+	if (ret != 0)
+		return ret;
+
+	return data;
+}
+
+/**
+ * of_davinci_aemif_parse_abus_config - parse bus config data from a cs node
+ * @np: device node ptr
+ *
+ * This function update the emif async bus configuration based on the values
+ * configured in a cs device binding node.
+ */
+static int of_davinci_aemif_parse_abus_config(struct device_node *np)
+{
+	struct davinci_aemif_cs_data *data;
+	int cs;
+
+
+	cs = dv_get_value(np, "cs");
+	if (cs < 2 || cs >= NUM_CS)
+		return -EINVAL;
+
+	if (aemif->cfg->num_cs >= NUM_CS)
+		return -EINVAL;
+
+	data = &aemif->cfg->cs_data[aemif->cfg->num_cs++];
+	data->cs	= cs;
+	data->ta	= dv_get_value(np, "ta");
+	data->rhold	= dv_get_value(np, "rhold");
+	data->rstrobe	= dv_get_value(np, "rstrobe");
+	data->rsetup	= dv_get_value(np, "rsetup");
+	data->whold	= dv_get_value(np, "whold");
+	data->wstrobe	= dv_get_value(np, "wstrobe");
+	data->wsetup	= dv_get_value(np, "wsetup");
+	data->asize	= dv_get_value(np, "asize");
+	data->enable_ew	= dv_get_value(np, "ew");
+	data->enable_ss	= dv_get_value(np, "ss");
+	return 0;
+}
+#endif
+
+static const struct of_device_id davinci_aemif_of_match[] __devinitconst = {
+	{ .compatible = "ti,davinci-aemif", },
+	{},
+};
+
+static const struct of_device_id davinci_cs_of_match[] __devinitconst = {
+	{ .compatible = "ti,davinci-cs", },
+	{},
+};
+
+/**
+ * of_davinci_aemif_cs_init - init cs data based on cs device nodes
+ * @np: device node ptr
+ *
+ * For every controller device node, there is a cs device node that
+ * describe the bus configuration parameters. This functions iterate
+ * over these nodes and update the cs data array.
+ */
+static int of_davinci_aemif_cs_init(struct device_node *aemif_np)
+{
+	struct device_node *np = aemif_np;
+
+	if (!np)
+		return -ENODEV;
+
+	for_each_matching_node(np, davinci_cs_of_match)
+		of_davinci_aemif_parse_abus_config(np);
+	return 0;
+}
+
+static int __devinit davinci_aemif_probe(struct platform_device *pdev)
+{
+	struct davinci_aemif_pdata *cfg;
+	int ret  = -ENODEV, i;
+	struct resource *res;
+
+	aemif = devm_kzalloc(&pdev->dev, sizeof(*aemif), GFP_KERNEL);
+
+	if (!aemif)
+		return -ENOMEM;
+
+	aemif->clk = clk_get(NULL, "aemif");
+	if (IS_ERR(aemif->clk))
+		return PTR_ERR(aemif->clk);
+
+	clk_prepare_enable(aemif->clk);
+
+	if (pdev->dev.platform_data == NULL) {
+		/* Not platform data, we get the cs data from the cs nodes */
+		cfg = devm_kzalloc(&pdev->dev, sizeof(*cfg), GFP_KERNEL);
+		if (cfg == NULL)
+			return -ENOMEM;
+
+		aemif->cfg = cfg;
+		if (of_davinci_aemif_cs_init(pdev->dev.of_node) < 0) {
+			pr_err("No platform data or cs of node present\n");
+			goto error;
+		}
+	} else {
+		cfg = pdev->dev.platform_data;
+		aemif->cfg = cfg;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		pr_err("No IO memory address defined\n");
+		goto error;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	aemif->base = devm_request_and_ioremap(&pdev->dev, res);
+	if (!aemif->base) {
+		ret = -EBUSY;
+		pr_err("ioremap failed\n");
+		goto error;
+	}
+
+	for (i = 0; i < cfg->num_cs; i++) {
+		ret = davinci_aemif_config_abus(cfg->cs_data[i].cs,
+				aemif->base, &cfg->cs_data[i]);
+		if (ret < 0) {
+			pr_err("Error configuring chip select %d\n",
+				cfg->cs_data[i].cs);
+			goto error;
+		}
+	}
+	return ret;
+error:
+	clk_disable_unprepare(aemif->clk);
+	clk_put(aemif->clk);
+	return ret;
+}
+
+static struct platform_driver davinci_aemif_driver = {
+	.probe = davinci_aemif_probe,
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = davinci_aemif_of_match,
+	},
+};
+
+static int __init davinci_aemif_init(void)
+{
+	return platform_driver_register(&davinci_aemif_driver);
+}
+subsys_initcall(davinci_aemif_init);
+
+static void __exit davinci_aemif_exit(void)
+{
+	clk_disable_unprepare(aemif->clk);
+	clk_put(aemif->clk);
+	platform_driver_unregister(&davinci_aemif_driver);
+}
+module_exit(davinci_aemif_exit);
+
+MODULE_AUTHOR("Murali Karicheri <m-karicheri2@xxxxxx>");
+MODULE_DESCRIPTION("Texas Instruments AEMIF driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/platform_data/davinci-aemif.h b/include/linux/platform_data/davinci-aemif.h
new file mode 100644
index 0000000..03f3ad0
--- /dev/null
+++ b/include/linux/platform_data/davinci-aemif.h
@@ -0,0 +1,47 @@
+/*
+ * 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)
+#define ASIZE_16BIT		1
+
+struct davinci_aemif_cs_data {
+	u8	cs;
+	u16	wstrobe;
+	u16	rstrobe;
+	u8	wsetup;
+	u8	whold;
+	u8	rsetup;
+	u8	rhold;
+	u8	ta;
+	u8	enable_ss;
+	u8	enable_ew;
+	u8	asize;
+};
+
+struct davinci_aemif_pdata {
+	u8	num_cs;
+	struct davinci_aemif_cs_data cs_data[4];
+};
+
+/* API to Get current Asynchrnous emif bus parameters */
+struct davinci_aemif_cs_data *davinci_aemif_get_abus_params(unsigned int cs);
+
+/* API to Set current Asynchrnous emif bus parameters */
+int davinci_aemif_set_abus_params(unsigned int cs,
+			struct davinci_aemif_cs_data *data);
+#endif
-- 
1.7.9.5

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