Re: [PATCH] mtd: plat_nand: add further DT bindings and documentation

[Alexander Clouter <alex@digriz.org.uk>]

Hi,

Anyone with any suggestions on what should be done with this patch? For my DT platform porting, 
is it okay for me to continue making use of this work?  Or is there a plan to kill plat-nand?

I am suspecting folks are aghast with horror at the thought of having plat-nand breeding with 
devicetree?

Cheers

On Sun, Mar 24, 2013 at 11:27:33AM +0000, Alexander Clouter wrote:
>The plat_nand driver has some devicetree support but it is currently
>unusable, especially as there is no documentation on how to use it.
>
>This patch adds the much needed documentation as well as adds some common
>properties (bank-width, chip-delay, bbt-use-flash and nr-chips) removing
>further use of the platform_nand_data struct.
>
>Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
>---
> .../devicetree/bindings/mtd/plat-nand.txt          |   93 ++++++++++++++++++++
> drivers/mtd/nand/plat_nand.c                       |   53 ++++++++---
> 2 files changed, 134 insertions(+), 12 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/mtd/plat-nand.txt
>
>diff --git a/Documentation/devicetree/bindings/mtd/plat-nand.txt b/Documentation/devicetree/bindings/mtd/plat-nand.txt
>new file mode 100644
>index 0000000..d534bfa
>--- /dev/null
>+++ b/Documentation/devicetree/bindings/mtd/plat-nand.txt
>@@ -0,0 +1,93 @@
>+NAND support for Generic NAND driver
>+
>+Required properties:
>+- compatible : "gen_nand"
>+- reg : Array of base physical addresses of the NAND and the length of memory
>+	mapped regions.  You *should* have a "nand_data" reg which is the
>+	data io region (if not named, then the first reg is used for
>+	IO_ADDR_R/IO_ADDR_W), additional regs are platform defined
>+- nr-chips : Number of physical chips
>+
>+Optional properties:
>+- reg-name : "nand_data" *should* be defined, additional ones are platform
>+		defined
>+- bank-width : Width in bytes of the device. Default is 1 (8bit), 2 (16bit)
>+		implies NAND_BUSWIDTH_16 and any other value is invalid
>+- chip-delay : Chip dependent delay for transferring data from array to read
>+		registers in usecs
>+- bbt-use-flash : Use a flash based bad block table.  Default, OOB identifier
>+		is saved in OOB area
>+
>+The device tree may optionally contain sub-nodes describing partitions of the
>+address space. See partition.txt for more detail.
>+
>+Example:
>+
>+nand@800 {
>+	#address-cells = <1>;
>+	#size-cells = <1>;
>+	compatible = "ts,nand", "gen_nand";
>+	reg =   <0x800 0x04>,
>+		<0x804 0x04>;
>+	reg-names = "nand_ctrl", "nand_data";
>+	nr-chips = <1>;
>+	chip-delay = <15>;
>+	bbt-use-flash;
>+
>+	partition@0 {
>+		label = "mbr";
>+		reg = <0x00000000 0x20000>;
>+		read-only;
>+	};
>+
>+	partition@20000 {
>+		label = "kernel";
>+		reg = <0x00020000 0x400000>;
>+	};
>+
>+	partition@420000 {
>+		label = "initrd";
>+		reg = <0x00420000 0x400000>;
>+	};
>+
>+	partition@820000 {
>+		label = "rootfs";
>+		reg = <0x00820000 0x1f7e0000>;
>+	};
>+};
>+
>+N.B. to use the plat-nand driver, the platform board code does still need to
>+	setup platform_nand_data and hook it into the platform_device so
>+	the callbacks (for at least .cmd_ctrl and .dev_ready) are available.
>+
>+Example:
>+
>+static struct platform_nand_data ts7800_nand_data = {
>+        .ctrl   = {
>+                .cmd_ctrl               = ts7800_nand_cmd_ctrl,
>+                .dev_ready              = ts7800_nand_dev_ready,
>+        },
>+};
>+
>+static int ts7800_platform_notifier(struct notifier_block *nb,
>+                                  unsigned long event, void *__dev)
>+{
>+        struct device *dev = __dev;
>+
>+        if (event != BUS_NOTIFY_ADD_DEVICE)
>+                return NOTIFY_DONE;
>+
>+        if (of_device_is_compatible(dev->of_node, "ts,nand"))
>+                dev->platform_data = &ts7800_nand_data;
>+
>+        return NOTIFY_OK;
>+}
>+
>+static struct notifier_block ts7800_platform_nb = {
>+        .notifier_call = ts7800_platform_notifier,
>+};
>+
>+void __init ts7800_init(void)
>+{
>+        bus_register_notifier(&platform_bus_type, &ts7800_platform_nb);
>+}
>diff --git a/drivers/mtd/nand/plat_nand.c b/drivers/mtd/nand/plat_nand.c
>index c004566..1407db5 100644
>--- a/drivers/mtd/nand/plat_nand.c
>+++ b/drivers/mtd/nand/plat_nand.c
>@@ -12,6 +12,7 @@
> #include <linux/io.h>
> #include <linux/module.h>
> #include <linux/platform_device.h>
>+#include <linux/of.h>
> #include <linux/slab.h>
> #include <linux/mtd/mtd.h>
> #include <linux/mtd/nand.h>
>@@ -23,7 +24,7 @@ struct plat_nand_data {
> 	void __iomem		*io_base;
> };
>
>-static const char *part_probe_types[] = { "cmdlinepart", NULL };
>+static const char *part_probe_types[] = { "cmdlinepart", "ofpart", NULL };
>
> /*
>  * Probe for the NAND device.
>@@ -42,14 +43,11 @@ static int plat_nand_probe(struct platform_device *pdev)
> 		return -EINVAL;
> 	}
>
>-	if (pdata->chip.nr_chips < 1) {
>-		dev_err(&pdev->dev, "invalid number of chips specified\n");
>-		return -EINVAL;
>-	}
>-
>-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "nand_data");
> 	if (!res)
>-		return -ENXIO;
>+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>+		if (!res)
>+			return -ENXIO;
>
> 	/* Allocate memory for the device structure (and zero it) */
> 	data = kzalloc(sizeof(struct plat_nand_data), GFP_KERNEL);
>@@ -79,15 +77,40 @@ static int plat_nand_probe(struct platform_device *pdev)
>
> 	data->chip.IO_ADDR_R = data->io_base;
> 	data->chip.IO_ADDR_W = data->io_base;
>+
>+	if (pdev->dev.of_node) {
>+		int i;
>+
>+		if (!of_property_read_u32(pdev->dev.of_node,
>+						"nr-chips", &i))
>+			data->chip.numchips = i;
>+		if (!of_property_read_u32(pdev->dev.of_node,
>+						"chip-delay", &i))
>+			data->chip.chip_delay = (u8)i;
>+		if (!of_property_read_u32(pdev->dev.of_node,
>+						"bank-width", &i)) {
>+			if (i == 2)
>+				data->chip.options |= NAND_BUSWIDTH_16;
>+			else if (i != 1) {
>+				dev_warn(&pdev->dev,
>+					"%d bit bus width out of range\n", i);
>+			}
>+		}
>+		if (of_get_property(pdev->dev.of_node, "bbt-use-flash", &i))
>+			data->chip.bbt_options |= NAND_BBT_USE_FLASH;
>+	} else {
>+		data->chip.numchips = pdata->chip.nr_chips;
>+		data->chip.chip_delay = pdata->chip.chip_delay;
>+		data->chip.options |= pdata->chip.options;
>+		data->chip.bbt_options |= pdata->chip.bbt_options;
>+	}
>+
> 	data->chip.cmd_ctrl = pdata->ctrl.cmd_ctrl;
> 	data->chip.dev_ready = pdata->ctrl.dev_ready;
> 	data->chip.select_chip = pdata->ctrl.select_chip;
> 	data->chip.write_buf = pdata->ctrl.write_buf;
> 	data->chip.read_buf = pdata->ctrl.read_buf;
> 	data->chip.read_byte = pdata->ctrl.read_byte;
>-	data->chip.chip_delay = pdata->chip.chip_delay;
>-	data->chip.options |= pdata->chip.options;
>-	data->chip.bbt_options |= pdata->chip.bbt_options;
>
> 	data->chip.ecc.hwctl = pdata->ctrl.hwcontrol;
> 	data->chip.ecc.layout = pdata->chip.ecclayout;
>@@ -102,8 +125,14 @@ static int plat_nand_probe(struct platform_device *pdev)
> 			goto out;
> 	}
>
>+	if (data->chip.numchips < 1) {
>+		dev_err(&pdev->dev, "invalid number of chips specified\n");
>+		err = -EINVAL;
>+		goto out;
>+	}
>+
> 	/* Scan to find existence of the device */
>-	if (nand_scan(&data->mtd, pdata->chip.nr_chips)) {
>+	if (nand_scan(&data->mtd, data->chip.numchips)) {
> 		err = -ENXIO;
> 		goto out;
> 	}
>-- 
>1.7.10.4
>

-- 
Alexander Clouter
.sigmonster says: Put your brain in gear before starting your mouth in motion.