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Message-ID: <20151026204900.GI13239@google.com>
Date: Mon, 26 Oct 2015 13:49:00 -0700
From: Brian Norris <computersforpeace@...il.com>
To: Roger Quadros <rogerq@...com>
Cc: tony@...mide.com, dwmw2@...radead.org,
ezequiel@...guardiasur.com.ar, javier@...hile0.org, fcooper@...com,
nsekhar@...com, linux-mtd@...ts.infradead.org,
linux-omap@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
Boris Brezillon <boris.brezillon@...e-electrons.com>,
Alex Smith <alex.smith@...tec.com>,
Harvey Hunt <harvey.hunt@...tec.com>
Subject: Re: [PATCH v3 18/27] mtd: nand: omap2: Implement NAND ready using
gpiolib
+ others
A few comments below.
On Fri, Sep 18, 2015 at 05:53:40PM +0300, Roger Quadros wrote:
> The GPMC WAIT pin status are now available over gpiolib.
> Update the omap_dev_ready() function to use gpio instead of
> directly accessing GPMC register space.
>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
> drivers/mtd/nand/omap2.c | 29 +++++++++++++++++-----------
> include/linux/platform_data/mtd-nand-omap2.h | 2 +-
> 2 files changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index 228f498..d0f2620 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -12,6 +12,7 @@
> #include <linux/dmaengine.h>
> #include <linux/dma-mapping.h>
> #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/module.h>
> #include <linux/interrupt.h>
> #include <linux/jiffies.h>
> @@ -184,6 +185,8 @@ struct omap_nand_info {
> /* fields specific for BCHx_HW ECC scheme */
> struct device *elm_dev;
> struct device_node *of_node;
> + /* NAND ready gpio */
> + struct gpio_desc *ready_gpiod;
> };
>
> /**
> @@ -1047,22 +1050,17 @@ static int omap_wait(struct mtd_info *mtd, struct nand_chip *chip)
> }
>
> /**
> - * omap_dev_ready - calls the platform specific dev_ready function
> + * omap_dev_ready - checks the NAND Ready GPIO line
> * @mtd: MTD device structure
> + *
> + * Returns true if ready and false if busy.
> */
> static int omap_dev_ready(struct mtd_info *mtd)
> {
> - unsigned int val = 0;
> struct omap_nand_info *info = container_of(mtd, struct omap_nand_info,
> mtd);
>
> - val = readl(info->reg.gpmc_status);
> -
> - if ((val & 0x100) == 0x100) {
> - return 1;
> - } else {
> - return 0;
> - }
> + return gpiod_get_value(info->ready_gpiod);
> }
>
> /**
> @@ -1782,7 +1780,9 @@ static int omap_nand_probe(struct platform_device *pdev)
> info->reg = pdata->reg;
> info->of_node = pdata->of_node;
> info->ecc_opt = pdata->ecc_opt;
> - info->dev_ready = pdata->dev_ready;
> + if (pdata->dev_ready)
> + dev_info(&pdev->dev, "pdata->dev_ready is deprecated\n");
> +
> info->xfer_type = pdata->xfer_type;
> info->devsize = pdata->devsize;
> info->elm_of_node = pdata->elm_of_node;
> @@ -1815,6 +1815,13 @@ static int omap_nand_probe(struct platform_device *pdev)
> nand_chip->IO_ADDR_W = nand_chip->IO_ADDR_R;
> nand_chip->cmd_ctrl = omap_hwcontrol;
>
> + info->ready_gpiod = devm_gpiod_get_optional(&pdev->dev, "ready",
> + GPIOD_IN);
Others have been looking at using GPIOs for the ready/busy pin too. At a
minimum, we need an updated DT binding doc for this, since I see you're
adding this via device tree in a later patch (I don't see any DT binding
patch for this; but I could just be overlooking it). It'd also be great
if this support was moved to nand_dt_init() so other platforms can
benefit, but I won't require that.
Also, previous [0] proposers had suggested 'rb-gpios', not 'ready-gpio'
(the hardware docs typically call it 'rb' for ready/busy, FWIW). I don't
really care, but the name should be going into a doc, so we can choose
the same one everywhere.
EDIT: looks like the discussion was partly here [1] and it seems we're
landing on "rb-gpios" in the latest version [2]. Can we stick with that?
Regards,
Brian
[0] "Previous" may be subject to debate, as both series have been going
for several revisions.
[1] http://patchwork.ozlabs.org/patch/515327/
[2] http://patchwork.ozlabs.org/patch/526819/
> + if (IS_ERR(info->ready_gpiod)) {
> + dev_err(dev, "failed to get ready gpio\n");
> + return PTR_ERR(info->ready_gpiod);
> + }
> +
> /*
> * If RDY/BSY line is connected to OMAP then use the omap ready
> * function and the generic nand_wait function which reads the status
> @@ -1822,7 +1829,7 @@ static int omap_nand_probe(struct platform_device *pdev)
> * chip delay which is slightly more than tR (AC Timing) of the NAND
> * device and read status register until you get a failure or success
> */
> - if (info->dev_ready) {
> + if (info->ready_gpiod) {
> nand_chip->dev_ready = omap_dev_ready;
> nand_chip->chip_delay = 0;
> } else {
> diff --git a/include/linux/platform_data/mtd-nand-omap2.h b/include/linux/platform_data/mtd-nand-omap2.h
> index ff27e5a..19e509d 100644
> --- a/include/linux/platform_data/mtd-nand-omap2.h
> +++ b/include/linux/platform_data/mtd-nand-omap2.h
> @@ -70,7 +70,6 @@ struct omap_nand_platform_data {
> int cs;
> struct mtd_partition *parts;
> int nr_parts;
> - bool dev_ready;
> bool flash_bbt;
> enum nand_io xfer_type;
> int devsize;
> @@ -81,5 +80,6 @@ struct omap_nand_platform_data {
> /* deprecated */
> struct gpmc_nand_regs reg;
> struct device_node *of_node;
> + bool dev_ready;
> };
> #endif
> --
> 2.1.4
>
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