Re: [PATCH v3 1/2] mtd: brcmnand: Force 8bit mode before doing nand_scan_ident()

[Brian Norris <computersforpeace@gmail.com>]

On Fri, Oct 23, 2015 at 10:46:12AM +0530, Anup Patel wrote:
> Just like other NAND controllers, the NAND READID command only works
> in 8bit mode for all versions of BRCMNAND controller.
> 
> This patch forces 8bit mode for each NAND CS in brcmnand_init_cs()
> before doing nand_scan_ident() to ensure that BRCMNAND controller
> is in 8bit mode when NAND READID command is issued.
> 
> Signed-off-by: Anup Patel <anup.patel@broadcom.com>
> Reviewed-by: Ray Jui <rjui@broadcom.com>
> Reviewed-by: Scott Branden <sbranden@broadcom.com>
> ---
>  drivers/mtd/nand/brcmnand/brcmnand.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
> index 4cba03d..0be8ef9 100644
> --- a/drivers/mtd/nand/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/brcmnand/brcmnand.c
> @@ -1888,6 +1888,7 @@ static int brcmnand_init_cs(struct brcmnand_host *host)
>  	struct mtd_info *mtd;
>  	struct nand_chip *chip;
>  	int ret;
> +	u16 cfg_offs;
>  	struct mtd_part_parser_data ppdata = { .of_node = dn };
>  
>  	ret = of_property_read_u32(dn, "reg", &host->cs);
> @@ -1930,6 +1931,14 @@ static int brcmnand_init_cs(struct brcmnand_host *host)
>  
>  	chip->controller = &ctrl->controller;
>  
> +	/*
> +	 * The bootloader might have configured 16bit mode but
> +	 * NAND READID command only works in 8bit mode. We force
> +	 * 8bit mode here to ensure that NAND READID commands works.
> +	 */
> +	cfg_offs = brcmnand_cs_offset(ctrl, host->cs, BRCMNAND_CS_CFG);
> +	nand_writereg(ctrl, cfg_offs, nand_readreg(ctrl, cfg_offs) & ~BIT(23));

Can we get a new enum for cfg bits? Unfortunately, I never managed that
in brcmnand_set_cfg(); just magic numbers :( But I'd like to stop that
if we're going to have to touch these bits outside of
brcmnand_set_cfg().

> +
>  	if (nand_scan_ident(mtd, 1, NULL))
>  		return -ENXIO;
>  

How about the following, as a preparatory patch? Only compile tested.

>From c5423a86dbfa33b550d2b170bda3c12ecf4d5313 Mon Sep 17 00:00:00 2001
From: Brian Norris <computersforpeace@gmail.com>
Date: Tue, 27 Oct 2015 17:12:13 -0700
Subject: [PATCH] mtd: brcmnand: factor out CFG and CFG_EXT bitfields

These used magic numbers. Shame on me.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Anup Patel <anup.patel@broadcom.com>
---
 drivers/mtd/nand/brcmnand/brcmnand.c | 38 +++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
index d694d876631e..c93fbc3869ee 100644
--- a/drivers/mtd/nand/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/brcmnand/brcmnand.c
@@ -344,6 +344,28 @@ static const u8 brcmnand_cs_offsets_cs0[] = {
 	[BRCMNAND_CS_TIMING2]		= 0x14,
 };
 
+/*
+ * Bitfields for the CFG and CFG_EXT registers. Pre-v7.1 controllers only had
+ * one config register, but once the bitfields overflowed, newer controllers
+ * (v7.1 and newer) added a CFG_EXT register and shuffled a few fields around.
+ */
+enum {
+	CFG_BLK_ADR_BYTES_SHIFT		= 8,
+	CFG_COL_ADR_BYTES_SHIFT		= 12,
+	CFG_FUL_ADR_BYTES_SHIFT		= 16,
+	CFG_BUS_WIDTH_SHIFT		= 23,
+	CFG_BUS_WIDTH			= BIT(CFG_BUS_WIDTH_SHIFT),
+	CFG_DEVICE_SIZE_SHIFT		= 24,
+
+	/* Only for pre-v7.1 (with no CFG_EXT register) */
+	CFG_PAGE_SIZE_SHIFT		= 20,
+	CFG_BLK_SIZE_SHIFT		= 28,
+
+	/* Only for v7.1+ (with CFG_EXT register) */
+	CFG_EXT_PAGE_SIZE_SHIFT		= 0,
+	CFG_EXT_BLK_SIZE_SHIFT		= 4,
+};
+
 /* BRCMNAND_INTFC_STATUS */
 enum {
 	INTFC_FLASH_STATUS		= GENMASK(7, 0),
@@ -1710,17 +1732,19 @@ static int brcmnand_set_cfg(struct brcmnand_host *host,
 	}
 	device_size = fls64(cfg->device_size) - fls64(BRCMNAND_MIN_DEVSIZE);
 
-	tmp = (cfg->blk_adr_bytes << 8) |
-		(cfg->col_adr_bytes << 12) |
-		(cfg->ful_adr_bytes << 16) |
-		(!!(cfg->device_width == 16) << 23) |
-		(device_size << 24);
+	tmp = (cfg->blk_adr_bytes << CFG_BLK_ADR_BYTES_SHIFT) |
+		(cfg->col_adr_bytes << CFG_BLK_ADR_BYTES_SHIFT) |
+		(cfg->ful_adr_bytes << CFG_FUL_ADR_BYTES_SHIFT) |
+		(!!(cfg->device_width == 16) << CFG_BUS_WIDTH_SHIFT) |
+		(device_size << CFG_DEVICE_SIZE_SHIFT);
 	if (cfg_offs == cfg_ext_offs) {
-		tmp |= (page_size << 20) | (block_size << 28);
+		tmp |= (page_size << CFG_PAGE_SIZE_SHIFT) |
+		       (block_size << CFG_BLK_SIZE_SHIFT);
 		nand_writereg(ctrl, cfg_offs, tmp);
 	} else {
 		nand_writereg(ctrl, cfg_offs, tmp);
-		tmp = page_size | (block_size << 4);
+		tmp = (page_size << CFG_EXT_PAGE_SIZE_SHIFT) |
+		      (block_size << CFG_EXT_BLK_SIZE_SHIFT);
 		nand_writereg(ctrl, cfg_ext_offs, tmp);
 	}
 
-- 
2.6.0.rc2.230.g3dd15c0