Patchwork [v3] mtd/maps: gpio-addr-flash: new driver for GPIO assisted flash addressing

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Submitter Mike Frysinger
Date Sept. 23, 2009, 4:48 a.m.
Message ID <1253681321-24600-1-git-send-email-vapier@gentoo.org>
Download mbox | patch
Permalink /patch/34114/
State Accepted, archived
Headers show

Comments

Mike Frysinger - Sept. 23, 2009, 4:48 a.m.
This driver lets people use GPIO's for additional address lines in case
their processor does not have enough address lines already.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
---
v3
	- rebase onto latest mainline
	- add missing GPIO dependency pointed out by David
	- switch to linux/*.h includes rather than asm/*.h includes

 drivers/mtd/maps/Kconfig           |   11 ++
 drivers/mtd/maps/Makefile          |    3 +-
 drivers/mtd/maps/gpio-addr-flash.c |  310 ++++++++++++++++++++++++++++++++++++
 3 files changed, 322 insertions(+), 2 deletions(-)
 create mode 100644 drivers/mtd/maps/gpio-addr-flash.c
David Woodhouse - Sept. 23, 2009, 7:16 a.m.
On Wed, 2009-09-23 at 00:48 -0400, Mike Frysinger wrote:
> 
> +       depends on GENERIC_GPIO || GPIOLIB

That still isn't right -- the failing case for me was when GENERIC_GPIO
was set but _not_ GPIOLIB.

I'll accept an answer of "that's because x86 gpio support is broken",
but you do have to handle the whining from the 'make randconfig' folks
for me :)

And please can you make it an incremental patch against what's in the
mtd-2.6.git tree (which I've already asked Linus to pull).
Mike Frysinger - Sept. 23, 2009, 2:54 p.m.
On Wed, Sep 23, 2009 at 03:16, David Woodhouse wrote:
> On Wed, 2009-09-23 at 00:48 -0400, Mike Frysinger wrote:
>>
>> +       depends on GENERIC_GPIO || GPIOLIB
>
> That still isn't right -- the failing case for me was when GENERIC_GPIO
> was set but _not_ GPIOLIB.
>
> I'll accept an answer of "that's because x86 gpio support is broken",
> but you do have to handle the whining from the 'make randconfig' folks
> for me :)

right, but this code doesnt depend on GPIOLIB.  it needs functioning
GPIO support and GENERIC_GPIO means the arch has a functioning GPIO
core for just the CPU pins.  i'm pretty sure x86 lies in this respect,
so hopefully this randconfig will poke the x86 guys to fix their tree
(or tell me where i'm wrong).  i looked at the x86 Kconfig and it
seems like it should be using "def_bool n" for this symbol, but i'm
not sure that'll fix things.

> And please can you make it an incremental patch against what's in the
> mtd-2.6.git tree (which I've already asked Linus to pull).

sorry, i didnt realize you merged it
-mike

Patch

diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
index 0f314eb..0fc67a2 100644
--- a/drivers/mtd/maps/Kconfig
+++ b/drivers/mtd/maps/Kconfig
@@ -484,6 +484,17 @@  config MTD_BFIN_ASYNC
 
 	  If compiled as a module, it will be called bfin-async-flash.
 
+config MTD_GPIO_ADDR
+	tristate "GPIO-assisted Flash Chip Support"
+	depends on GENERIC_GPIO || GPIOLIB
+	depends on MTD_COMPLEX_MAPPINGS
+	select MTD_PARTITIONS
+	help
+	  Map driver which allows flashes to be partially physically addressed
+	  and assisted by GPIOs.
+
+	  If compiled as a module, it will be called gpio-addr-flash.
+
 config MTD_UCLINUX
 	bool "Generic uClinux RAM/ROM filesystem support"
 	depends on MTD_PARTITIONS && MTD_RAM=y && !MMU
diff --git a/drivers/mtd/maps/Makefile b/drivers/mtd/maps/Makefile
index 5beb066..1d5cf86 100644
--- a/drivers/mtd/maps/Makefile
+++ b/drivers/mtd/maps/Makefile
@@ -58,5 +58,4 @@  obj-$(CONFIG_MTD_PLATRAM)	+= plat-ram.o
 obj-$(CONFIG_MTD_OMAP_NOR)	+= omap_nor.o
 obj-$(CONFIG_MTD_INTEL_VR_NOR)	+= intel_vr_nor.o
 obj-$(CONFIG_MTD_BFIN_ASYNC)	+= bfin-async-flash.o
-obj-$(CONFIG_MTD_RBTX4939)	+= rbtx4939-flash.o
-obj-$(CONFIG_MTD_VMU)		+= vmu-flash.o
+obj-$(CONFIG_MTD_GPIO_ADDR)	+= gpio-addr-flash.o
diff --git a/drivers/mtd/maps/gpio-addr-flash.c b/drivers/mtd/maps/gpio-addr-flash.c
new file mode 100644
index 0000000..844a7a5
--- /dev/null
+++ b/drivers/mtd/maps/gpio-addr-flash.c
@@ -0,0 +1,310 @@ 
+/*
+ * drivers/mtd/maps/gpio-addr-flash.c
+ *
+ * Handle the case where a flash device is mostly addressed using physical
+ * line and supplemented by GPIOs.  This way you can hook up say a 8meg flash
+ * to a 2meg memory range and use the GPIOs to select a particular range.
+ *
+ * Copyright 2000 Nicolas Pitre <nico@cam.org>
+ * Copyright 2005-2009 Analog Devices Inc.
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/physmap.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+
+#define pr_devinit(fmt, args...) ({ static const __devinitconst char __fmt[] = fmt; printk(__fmt, ## args); })
+
+#define DRIVER_NAME "gpio-addr-flash"
+#define PFX DRIVER_NAME ": "
+
+/**
+ * struct async_state - keep GPIO flash state
+ *	@mtd:         MTD state for this mapping
+ *	@map:         MTD map state for this flash
+ *	@gpio_count:  number of GPIOs used to address
+ *	@gpio_addrs:  array of GPIOs to twiddle
+ *	@gpio_values: cached GPIO values
+ *	@win_size:    dedicated memory size (if no GPIOs)
+ */
+struct async_state {
+	struct mtd_info *mtd;
+	struct map_info map;
+	size_t gpio_count;
+	unsigned *gpio_addrs;
+	int *gpio_values;
+	unsigned long win_size;
+};
+#define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1)
+
+/**
+ * gf_set_gpios() - set GPIO address lines to access specified flash offset
+ *	@state: GPIO flash state
+ *	@ofs:   desired offset to access
+ *
+ * Rather than call the GPIO framework every time, cache the last-programmed
+ * value.  This speeds up sequential accesses (which are by far the most common
+ * type).  We rely on the GPIO framework to treat non-zero value as high so
+ * that we don't have to normalize the bits.
+ */
+static void gf_set_gpios(struct async_state *state, unsigned long ofs)
+{
+	size_t i = 0;
+	int value;
+	ofs /= state->win_size;
+	do {
+		value = ofs & (1 << i);
+		if (state->gpio_values[i] != value) {
+			gpio_set_value(state->gpio_addrs[i], value);
+			state->gpio_values[i] = value;
+		}
+	} while (++i < state->gpio_count);
+}
+
+/**
+ * gf_read() - read a word at the specified offset
+ *	@map: MTD map state
+ *	@ofs: desired offset to read
+ */
+static map_word gf_read(struct map_info *map, unsigned long ofs)
+{
+	struct async_state *state = gf_map_info_to_state(map);
+	u16 word;
+	map_word test;
+
+	gf_set_gpios(state, ofs);
+
+	word = readw(map->virt + (ofs % state->win_size));
+	test.x[0] = word;
+	return test;
+}
+
+/**
+ * gf_copy_from() - copy a chunk of data from the flash
+ *	@map:  MTD map state
+ *	@to:   memory to copy to
+ *	@from: flash offset to copy from
+ *	@len:  how much to copy
+ *
+ * We rely on the MTD layer to chunk up copies such that a single request here
+ * will not cross a window size.  This allows us to only wiggle the GPIOs once
+ * before falling back to a normal memcpy.  Reading the higher layer code shows
+ * that this is indeed the case, but add a BUG_ON() to future proof.
+ */
+static void gf_copy_from(struct map_info *map, void *to, unsigned long from, ssize_t len)
+{
+	struct async_state *state = gf_map_info_to_state(map);
+
+	gf_set_gpios(state, from);
+
+	/* BUG if operation crosses the win_size */
+	BUG_ON(!((from + len) % state->win_size <= (from + len)));
+
+	/* operation does not cross the win_size, so one shot it */
+	memcpy_fromio(to, map->virt + (from % state->win_size), len);
+}
+
+/**
+ * gf_write() - write a word at the specified offset
+ *	@map: MTD map state
+ *	@ofs: desired offset to write
+ */
+static void gf_write(struct map_info *map, map_word d1, unsigned long ofs)
+{
+	struct async_state *state = gf_map_info_to_state(map);
+	u16 d;
+
+	gf_set_gpios(state, ofs);
+
+	d = d1.x[0];
+	writew(d, map->virt + (ofs % state->win_size));
+}
+
+/**
+ * gf_copy_to() - copy a chunk of data to the flash
+ *	@map:  MTD map state
+ *	@to:   flash offset to copy to
+ *	@from: memory to copy from
+ *	@len:  how much to copy
+ *
+ * See gf_copy_from() caveat.
+ */
+static void gf_copy_to(struct map_info *map, unsigned long to, const void *from, ssize_t len)
+{
+	struct async_state *state = gf_map_info_to_state(map);
+
+	gf_set_gpios(state, to);
+
+	/* BUG if operation crosses the win_size */
+	BUG_ON(!((to + len) % state->win_size <= (to + len)));
+
+	/* operation does not cross the win_size, so one shot it */
+	memcpy_toio(map->virt + (to % state->win_size), from, len);
+}
+
+#ifdef CONFIG_MTD_PARTITIONS
+static const char *part_probe_types[] = { "cmdlinepart", "RedBoot", NULL };
+#endif
+
+/**
+ * gpio_flash_probe() - setup a mapping for a GPIO assisted flash
+ *	@pdev: platform device
+ *
+ * The platform resource layout expected looks something like:
+ * struct mtd_partition partitions[] = { ... };
+ * struct physmap_flash_data flash_data = { ... };
+ * unsigned flash_gpios[] = { GPIO_XX, GPIO_XX, ... };
+ * struct resource flash_resource[] = {
+ *	{
+ *		.name  = "cfi_probe",
+ *		.start = 0x20000000,
+ *		.end   = 0x201fffff,
+ *		.flags = IORESOURCE_MEM,
+ *	}, {
+ *		.start = (unsigned long)flash_gpios,
+ *		.end   = ARRAY_SIZE(flash_gpios),
+ *		.flags = IORESOURCE_IRQ,
+ *	}
+ * };
+ * struct platform_device flash_device = {
+ *	.name          = "gpio-addr-flash",
+ *	.dev           = { .platform_data = &flash_data, },
+ *	.num_resources = ARRAY_SIZE(flash_resource),
+ *	.resource      = flash_resource,
+ *	...
+ * };
+ */
+static int __devinit gpio_flash_probe(struct platform_device *pdev)
+{
+	int ret;
+	size_t i, arr_size;
+	struct physmap_flash_data *pdata;
+	struct resource *memory;
+	struct resource *gpios;
+	struct async_state *state;
+
+	pdata = pdev->dev.platform_data;
+	memory = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	gpios = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+
+	if (!memory || !gpios || !gpios->end)
+		return -EINVAL;
+
+	arr_size = sizeof(int) * gpios->end;
+	state = kzalloc(sizeof(*state) + arr_size, GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	state->gpio_count     = gpios->end;
+	state->gpio_addrs     = (void *)gpios->start;
+	state->gpio_values    = (void *)(state + 1);
+	state->win_size       = memory->end - memory->start + 1;
+	memset(state->gpio_values, 0xff, arr_size);
+
+	state->map.name       = DRIVER_NAME;
+	state->map.read       = gf_read;
+	state->map.copy_from  = gf_copy_from;
+	state->map.write      = gf_write;
+	state->map.copy_to    = gf_copy_to;
+	state->map.bankwidth  = pdata->width;
+	state->map.size       = state->win_size * (1 << state->gpio_count);
+	state->map.virt       = (void __iomem *)memory->start;
+	state->map.phys       = NO_XIP;
+	state->map.map_priv_1 = (unsigned long)state;
+
+	platform_set_drvdata(pdev, state);
+
+	i = 0;
+	do {
+		if (gpio_request(state->gpio_addrs[i], DRIVER_NAME)) {
+			pr_devinit(KERN_ERR PFX "failed to request gpio %d\n",
+				state->gpio_addrs[i]);
+			while (i--)
+				gpio_free(state->gpio_addrs[i]);
+			kfree(state);
+			return -EBUSY;
+		}
+		gpio_direction_output(state->gpio_addrs[i], 0);
+	} while (++i < state->gpio_count);
+
+	pr_devinit(KERN_NOTICE PFX "probing %d-bit flash bus\n",
+		state->map.bankwidth * 8);
+	state->mtd = do_map_probe(memory->name, &state->map);
+	if (!state->mtd) {
+		for (i = 0; i < state->gpio_count; ++i)
+			gpio_free(state->gpio_addrs[i]);
+		kfree(state);
+		return -ENXIO;
+	}
+
+#ifdef CONFIG_MTD_PARTITIONS
+	ret = parse_mtd_partitions(state->mtd, part_probe_types, &pdata->parts, 0);
+	if (ret > 0) {
+		pr_devinit(KERN_NOTICE PFX "Using commandline partition definition\n");
+		add_mtd_partitions(state->mtd, pdata->parts, ret);
+		kfree(pdata->parts);
+
+	} else if (pdata->nr_parts) {
+		pr_devinit(KERN_NOTICE PFX "Using board partition definition\n");
+		add_mtd_partitions(state->mtd, pdata->parts, pdata->nr_parts);
+
+	} else
+#endif
+	{
+		pr_devinit(KERN_NOTICE PFX "no partition info available, registering whole flash at once\n");
+		add_mtd_device(state->mtd);
+	}
+
+	return 0;
+}
+
+static int __devexit gpio_flash_remove(struct platform_device *pdev)
+{
+	struct async_state *state = platform_get_drvdata(pdev);
+	size_t i = 0;
+	do {
+		gpio_free(state->gpio_addrs[i]);
+	} while (++i < state->gpio_count);
+#ifdef CONFIG_MTD_PARTITIONS
+	del_mtd_partitions(state->mtd);
+#endif
+	map_destroy(state->mtd);
+	kfree(state);
+	return 0;
+}
+
+static struct platform_driver gpio_flash_driver = {
+	.probe		= gpio_flash_probe,
+	.remove		= __devexit_p(gpio_flash_remove),
+	.driver		= {
+		.name	= DRIVER_NAME,
+	},
+};
+
+static int __init gpio_flash_init(void)
+{
+	return platform_driver_register(&gpio_flash_driver);
+}
+module_init(gpio_flash_init);
+
+static void __exit gpio_flash_exit(void)
+{
+	platform_driver_unregister(&gpio_flash_driver);
+}
+module_exit(gpio_flash_exit);
+
+MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
+MODULE_DESCRIPTION("MTD map driver for flashes addressed physically and with gpios");
+MODULE_LICENSE("GPL");