[PATCH V5 06/10] MIPS: lantiq: add NOR flash support

[PATCH V5 06/10] MIPS: lantiq: add NOR flash support

[John Crispin]

NOR flash is attached to the same EBU (External Bus Unit) as PCI. As described
in the PCI patch, the EBU is a little buggy, resulting in the upper and lower
16 bit of the data on a 32 bit read are swapped. (essentially we have a addr^=2)

To work around this we do a addr^=2 during the probe. Once probed we adapt
cfi->addr_unlock1 and cfi->addr_unlock2 to represent the endianess bug.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Ralph Hempel <ralph.hempel@lantiq.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-mtd@lists.infradead.org

---

Changes in V2
* handle the endianess bug inside the map code and not in the generic cfi code
* remove the addr swizzle patch

Changes in V3
* whitespace
* change __iomem void to void __iomem

Chanegs in V4
* fixes a checkpatch.pl bug, the second is a false positive
* whitespace cleanups
* remove unused typecasts
* cleanup ltq_copy_from and ltq_copy_to

 drivers/mtd/maps/Kconfig  |    9 ++
 drivers/mtd/maps/Makefile |    1 +
 drivers/mtd/maps/lantiq.c |  181 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 191 insertions(+), 0 deletions(-)
 create mode 100644 drivers/mtd/maps/lantiq.c

diff --git a/drivers/mtd/maps/Kconfig b/drivers/mtd/maps/Kconfig
index 44b1f46..83376d3 100644
--- a/drivers/mtd/maps/Kconfig
+++ b/drivers/mtd/maps/Kconfig
@@ -260,6 +260,15 @@ config MTD_BCM963XX
 	  Support for parsing CFE image tag and creating MTD partitions on
 	  Broadcom BCM63xx boards.
 
+config MTD_LANTIQ
+	bool "Lantiq SoC NOR support"
+	depends on LANTIQ
+	select MTD_PARTITIONS
+	help
+	  Lantiq SoCs have a EBU (External Bus Unit). This IP allows to attach
+	  a number of different peripherals to the SoC. This driver adds
+	  support for NOR chips to be added.
+
 config MTD_DILNETPC
 	tristate "CFI Flash device mapped on DIL/Net PC"
 	depends on X86 && MTD_PARTITIONS && MTD_CFI_INTELEXT && BROKEN
diff --git a/drivers/mtd/maps/Makefile b/drivers/mtd/maps/Makefile
index 08533bd..0db4ba3 100644
--- a/drivers/mtd/maps/Makefile
+++ b/drivers/mtd/maps/Makefile
@@ -60,3 +60,4 @@ obj-$(CONFIG_MTD_VMU)		+= vmu-flash.o
 obj-$(CONFIG_MTD_GPIO_ADDR)	+= gpio-addr-flash.o
 obj-$(CONFIG_MTD_BCM963XX)	+= bcm963xx-flash.o
 obj-$(CONFIG_MTD_LATCH_ADDR)	+= latch-addr-flash.o
+obj-$(CONFIG_MTD_LANTIQ)	+= lantiq.o
diff --git a/drivers/mtd/maps/lantiq.c b/drivers/mtd/maps/lantiq.c
new file mode 100644
index 0000000..96a0b57
--- /dev/null
+++ b/drivers/mtd/maps/lantiq.c
@@ -0,0 +1,181 @@
+/*
+ *  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.
+ *
+ *  Copyright (C) 2004 Liu Peng Infineon IFAP DC COM CPE
+ *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/cfi.h>
+#include <linux/platform_device.h>
+#include <linux/mtd/physmap.h>
+
+#include <lantiq_soc.h>
+#include <lantiq_platform.h>
+
+/* the NOR flash is connected to the same external bus unit (EBU) as PCI.
+ * To make PCI work we need to enable the endianess swapping of the addr
+ * written to the EBU. this however has some limitations and breaks when
+ * using NOR. it does not really matter if the onflash data is in a swapped
+ * order, however cfi sequences also fail. to workaround this we need to use
+ * a complex map. We essentially software swap all addresses during probe
+ * and then swizzle the unlock addresses.
+ */
+static int ltq_mtd_probing;
+
+static map_word
+ltq_read16(struct map_info *map, unsigned long adr)
+{
+	unsigned long flags;
+	map_word temp;
+
+	if (ltq_mtd_probing)
+		adr ^= 2;
+	spin_lock_irqsave(&ebu_lock, flags);
+	temp.x[0] = *((__u16 *)(map->virt + adr));
+	spin_unlock_irqrestore(&ebu_lock, flags);
+	return temp;
+}
+
+static void
+ltq_write16(struct map_info *map, map_word d, unsigned long adr)
+{
+	unsigned long flags;
+
+	if (ltq_mtd_probing)
+		adr ^= 2;
+	spin_lock_irqsave(&ebu_lock, flags);
+	*((__u16 *)(map->virt + adr)) = d.x[0];
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+static void
+ltq_copy_from(struct map_info *map, void *to,
+	unsigned long from, ssize_t len)
+{
+	unsigned char *f = (unsigned char *) (map->virt + from);
+	unsigned char *t = (unsigned char *) to;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ebu_lock, flags);
+	while (len--)
+		*t++ = *f++;
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+static void
+ltq_copy_to(struct map_info *map, unsigned long to,
+	const void *from, ssize_t len)
+{
+	unsigned char *f = (unsigned char *) from;
+	unsigned char *t = (unsigned char *) (map->virt + to);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ebu_lock, flags);
+	while (len--)
+		*t++ = *f++;
+	spin_unlock_irqrestore(&ebu_lock, flags);
+}
+
+static const char const *part_probe_types[] = {
+	"cmdlinepart", NULL };
+
+static struct map_info ltq_map = {
+	.name = "ltq_nor",
+	.bankwidth = 2,
+	.read = ltq_read16,
+	.write = ltq_write16,
+	.copy_from = ltq_copy_from,
+	.copy_to = ltq_copy_to,
+};
+
+static int __init
+ltq_mtd_probe(struct platform_device *pdev)
+{
+	struct physmap_flash_data *ltq_mtd_data =
+		dev_get_platdata(&pdev->dev);
+	struct mtd_info *ltq_mtd = NULL;
+	struct mtd_partition *parts = NULL;
+	struct resource *res = 0;
+	int nr_parts = 0;
+	struct cfi_private *cfi;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "failed to get memory resource");
+		return -ENOENT;
+	}
+	res = devm_request_mem_region(&pdev->dev, res->start,
+		resource_size(res), dev_name(&pdev->dev));
+	if (!res) {
+		dev_err(&pdev->dev, "failed to request mem resource");
+		return -EBUSY;
+	}
+
+	ltq_map.phys = res->start;
+	ltq_map.size = resource_size(res);
+	ltq_map.virt = devm_ioremap_nocache(&pdev->dev, ltq_map.phys,
+					ltq_map.size);
+	if (!ltq_map.virt) {
+		dev_err(&pdev->dev, "failed to ioremap!\n");
+		return -EIO;
+	}
+
+	ltq_mtd_probing = 1;
+	ltq_mtd = do_map_probe("cfi_probe", &ltq_map);
+	ltq_mtd_probing = 0;
+	if (!ltq_mtd) {
+		iounmap(ltq_map.virt);
+		dev_err(&pdev->dev, "probing failed\n");
+		return -ENXIO;
+	}
+	ltq_mtd->owner = THIS_MODULE;
+
+	cfi = ltq_map.fldrv_priv;
+	cfi->addr_unlock1 ^= 1;
+	cfi->addr_unlock2 ^= 1;
+
+	nr_parts = parse_mtd_partitions(ltq_mtd, part_probe_types, &parts, 0);
+	if (nr_parts > 0) {
+		dev_info(&pdev->dev,
+			"using %d partitions from cmdline", nr_parts);
+	} else {
+		nr_parts = ltq_mtd_data->nr_parts;
+		parts = ltq_mtd_data->parts;
+	}
+
+	add_mtd_partitions(ltq_mtd, parts, nr_parts);
+	return 0;
+}
+
+static struct platform_driver ltq_mtd_driver = {
+	.driver = {
+		.name = "ltq_nor",
+		.owner = THIS_MODULE,
+	},
+};
+
+int __init
+init_ltq_mtd(void)
+{
+	int ret = platform_driver_probe(&ltq_mtd_driver, ltq_mtd_probe);
+
+	if (ret)
+		printk(KERN_INFO "ltq_nor: error registering platfom driver");
+	return ret;
+}
+
+module_init(init_ltq_mtd);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
+MODULE_DESCRIPTION("Lantiq SoC NOR");
-- 
1.7.2.3

Re: [PATCH V5 06/10] MIPS: lantiq: add NOR flash support

[Artem Bityutskiy]

Hi,

just few minor things.

On Wed, 2011-03-30 at 09:27 +0200, John Crispin wrote:
> +/* the NOR flash is connected to the same external bus unit (EBU) as PCI.
> + * To make PCI work we need to enable the endianess swapping of the addr
> + * written to the EBU. this however has some limitations and breaks when
> + * using NOR. it does not really matter if the onflash data is in a swapped
> + * order, however cfi sequences also fail. to workaround this we need to use
> + * a complex map. We essentially software swap all addresses during probe
> + * and then swizzle the unlock addresses.
> + */

Would be nice to clean-up the comment a little bit and use capital
letters at the start of the sentences. Also, I think the style for
multi-line comments is:

/*
 * bla
 * bla
 */


> +static void
> +ltq_copy_from(struct map_info *map, void *to,
> +	unsigned long from, ssize_t len)
> +{
> +	unsigned char *f = (unsigned char *) (map->virt + from);
> +	unsigned char *t = (unsigned char *) to;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&ebu_lock, flags);
> +	while (len--)
> +		*t++ = *f++;
> +	spin_unlock_irqrestore(&ebu_lock, flags);

Can you use memcpy here instead?

> +}
> +
> +static void
> +ltq_copy_to(struct map_info *map, unsigned long to,
> +	const void *from, ssize_t len)
> +{
> +	unsigned char *f = (unsigned char *) from;
> +	unsigned char *t = (unsigned char *) (map->virt + to);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&ebu_lock, flags);
> +	while (len--)
> +		*t++ = *f++;

Can you use memcpy here instead?

> +	spin_unlock_irqrestore(&ebu_lock, flags);
> +}
> +
> +static const char const *part_probe_types[] = {
> +	"cmdlinepart", NULL };

This can be one-liner, no need to make 2  lines.

> +
> +static struct map_info ltq_map = {
> +	.name = "ltq_nor",
> +	.bankwidth = 2,
> +	.read = ltq_read16,
> +	.write = ltq_write16,
> +	.copy_from = ltq_copy_from,
> +	.copy_to = ltq_copy_to,
> +};
> +
> +static int __init
> +ltq_mtd_probe(struct platform_device *pdev)
> +{
> +	struct physmap_flash_data *ltq_mtd_data =
> +		dev_get_platdata(&pdev->dev);

This can be one line - it takes only 79 characters.

> +	struct mtd_info *ltq_mtd = NULL;
> +	struct mtd_partition *parts = NULL;
> +	struct resource *res = 0;
You do not need this initialization.

> +	int nr_parts = 0;
> +	struct cfi_private *cfi;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(&pdev->dev, "failed to get memory resource");
> +		return -ENOENT;
> +	}
> +	res = devm_request_mem_region(&pdev->dev, res->start,
> +		resource_size(res), dev_name(&pdev->dev));
> +	if (!res) {
> +		dev_err(&pdev->dev, "failed to request mem resource");
> +		return -EBUSY;
> +	}
> +
> +	ltq_map.phys = res->start;
> +	ltq_map.size = resource_size(res);
> +	ltq_map.virt = devm_ioremap_nocache(&pdev->dev, ltq_map.phys,
> +					ltq_map.size);
> +	if (!ltq_map.virt) {
> +		dev_err(&pdev->dev, "failed to ioremap!\n");
> +		return -EIO;
> +	}
> +
> +	ltq_mtd_probing = 1;
> +	ltq_mtd = do_map_probe("cfi_probe", &ltq_map);
> +	ltq_mtd_probing = 0;
> +	if (!ltq_mtd) {
> +		iounmap(ltq_map.virt);
> +		dev_err(&pdev->dev, "probing failed\n");
> +		return -ENXIO;
> +	}
> +	ltq_mtd->owner = THIS_MODULE;
> +
> +	cfi = ltq_map.fldrv_priv;
> +	cfi->addr_unlock1 ^= 1;
> +	cfi->addr_unlock2 ^= 1;
> +
> +	nr_parts = parse_mtd_partitions(ltq_mtd, part_probe_types, &parts, 0);
> +	if (nr_parts > 0) {
> +		dev_info(&pdev->dev,
> +			"using %d partitions from cmdline", nr_parts);
> +	} else {
> +		nr_parts = ltq_mtd_data->nr_parts;
> +		parts = ltq_mtd_data->parts;
> +	}
> +
> +	add_mtd_partitions(ltq_mtd, parts, nr_parts);

This function may return an error.

> +	return 0;
> +}
> +
> +static struct platform_driver ltq_mtd_driver = {
> +	.driver = {
> +		.name = "ltq_nor",
> +		.owner = THIS_MODULE,
> +	},
> +};
> +
> +int __init
> +init_ltq_mtd(void)
> +{
> +	int ret = platform_driver_probe(&ltq_mtd_driver, ltq_mtd_probe);
> +
> +	if (ret)
> +		printk(KERN_INFO "ltq_nor: error registering platfom driver");

I think errors should be printed with KERN_ERR level. Anyway, use
pr_err() here instead pleas.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

Re: [PATCH V5 06/10] MIPS: lantiq: add NOR flash support

[John Crispin]

Hi Artem

thanks for the feedback, comments inline
>
>> +ltq_copy_from(struct map_info *map, void *to,
>> +	unsigned long from, ssize_t len)
>> +{
>> +	unsigned char *f = (unsigned char *) (map->virt + from);
>> +	unsigned char *t = (unsigned char *) to;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&ebu_lock, flags);
>> +	while (len--)
>> +		*t++ = *f++;
>> +	spin_unlock_irqrestore(&ebu_lock, flags);
>>     
> Can you use memcpy here instead?
>
>   

as we are copying to/from iomem, we cannot use memcpy as the
pre-fetching breaks the copy process. the normal alternative is to use
memcpy_to/fromio, however on MIPS this breaks down to a normal memcpy.

i will fold your comments into the patch and resend it ASAP

thanks, John

Re: [PATCH V5 06/10] MIPS: lantiq: add NOR flash support

[Artem Bityutskiy]

On Mon, 2011-04-04 at 15:36 +0200, John Crispin wrote:
> >> +ltq_copy_from(struct map_info *map, void *to,
> >> +	unsigned long from, ssize_t len)
> >> +{
> >> +	unsigned char *f = (unsigned char *) (map->virt + from);
> >> +	unsigned char *t = (unsigned char *) to;
> >> +	unsigned long flags;
> >> +
> >> +	spin_lock_irqsave(&ebu_lock, flags);
> >> +	while (len--)
> >> +		*t++ = *f++;
> >> +	spin_unlock_irqrestore(&ebu_lock, flags);
> >>     
> > Can you use memcpy here instead?
> >
> >   
> as we are copying to/from iomem, we cannot use memcpy as the
> pre-fetching breaks the copy process. the normal alternative is to use
> memcpy_to/fromio, however on MIPS this breaks down to a normal memcpy.

Would be nice to have this comment in the code to make life of those who
reads it a bit easier.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)