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Message-ID: <562F2FB6.7050806@ti.com>
Date: Tue, 27 Oct 2015 10:03:02 +0200
From: Roger Quadros <rogerq@...com>
To: Brian Norris <computersforpeace@...il.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
On 26/10/15 22:49, Brian Norris wrote:
> + 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?
Why should it be "rb-gpios" and not "rb-gpio"?
I don't think there are multiple gpios for r/b# function.
cheers,
-roger
>
> 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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