linux-kernel - Re: [PATCH v3 2/2] mtd: rawnand: meson: waiting w/o wired ready/busy pin

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Message-ID: <73849b9c-0700-4946-84a2-428f98f0a6d6@sberdevices.ru>
Date:   Tue, 4 Jul 2023 16:07:56 +0300
From:   Arseniy Krasnov <avkrasnov@...rdevices.ru>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
CC:     Liang Yang <liang.yang@...ogic.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        <oxffffaa@...il.com>, <kernel@...rdevices.ru>,
        <linux-mtd@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] mtd: rawnand: meson: waiting w/o wired ready/busy
 pin



On 04.07.2023 16:12, Miquel Raynal wrote:
> Hi Arseniy,
> 
> avkrasnov@...rdevices.ru wrote on Tue, 4 Jul 2023 15:46:18 +0300:
> 
>> On 04.07.2023 15:43, Miquel Raynal wrote:
>>> Hi Arseniy,
>>>
>>> AVKrasnov@...rdevices.ru wrote on Thu, 8 Jun 2023 07:47:28 +0300:
>>>   
>>>> If there is no wired ready/busy pin, classic way to wait for command
>>>> completion is to use function 'nand_soft_waitrdy()'. Meson NAND has
>>>> special command which allows to wait for NAND_STATUS_READY bit without
>>>> reading status in a software loop (as 'nand_soft_waitrdy()' does). To
>>>> use it send this command along with NAND_CMD_STATUS, then wait for an
>>>> interrupt, and after interrupt send NAND_CMD_READ0. So this feature
>>>> allows to use interrupt driven waiting without wired ready/busy pin.
>>>>
>>>> Suggested-by: Liang Yang <liang.yang@...ogic.com>
>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
>>>> ---
>>>>  drivers/mtd/nand/raw/meson_nand.c | 77 +++++++++++++++++++++++++++++--
>>>>  1 file changed, 73 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
>>>> index 074e14225c06..9f05e113b4ea 100644
>>>> --- a/drivers/mtd/nand/raw/meson_nand.c
>>>> +++ b/drivers/mtd/nand/raw/meson_nand.c
>>>> @@ -38,6 +38,7 @@
>>>>  #define NFC_CMD_SCRAMBLER_DISABLE	0
>>>>  #define NFC_CMD_SHORTMODE_DISABLE	0
>>>>  #define NFC_CMD_RB_INT		BIT(14)
>>>> +#define NFC_CMD_RB_INT_NO_PIN	((0xb << 10) | BIT(18) | BIT(16))
>>>>  
>>>>  #define NFC_CMD_GET_SIZE(x)	(((x) >> 22) & GENMASK(4, 0))
>>>>  
>>>> @@ -179,6 +180,7 @@ struct meson_nfc {
>>>>  	u32 info_bytes;
>>>>  
>>>>  	unsigned long assigned_cs;
>>>> +	bool no_rb_pin;
>>>>  };
>>>>  
>>>>  enum {
>>>> @@ -392,7 +394,42 @@ static void meson_nfc_set_data_oob(struct nand_chip *nand,
>>>>  	}
>>>>  }
>>>>  
>>>> -static int meson_nfc_queue_rb(struct meson_nfc *nfc, int timeout_ms)
>>>> +static int meson_nfc_wait_no_rb_pin(struct meson_nfc *nfc, int timeout_ms,
>>>> +				    bool need_cmd_read0)
>>>> +{
>>>> +	u32 cmd, cfg;
>>>> +
>>>> +	meson_nfc_cmd_idle(nfc, nfc->timing.twb);
>>>> +	meson_nfc_drain_cmd(nfc);
>>>> +	meson_nfc_wait_cmd_finish(nfc, CMD_FIFO_EMPTY_TIMEOUT);
>>>> +
>>>> +	cfg = readl(nfc->reg_base + NFC_REG_CFG);
>>>> +	cfg |= NFC_RB_IRQ_EN;
>>>> +	writel(cfg, nfc->reg_base + NFC_REG_CFG);
>>>> +
>>>> +	reinit_completion(&nfc->completion);
>>>> +	cmd = nfc->param.chip_select | NFC_CMD_CLE | NAND_CMD_STATUS;
>>>> +	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>> +
>>>> +	/* use the max erase time as the maximum clock for waiting R/B */
>>>> +	cmd = NFC_CMD_RB | NFC_CMD_RB_INT_NO_PIN | nfc->timing.tbers_max;
>>>> +	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>> +
>>>> +	if (!wait_for_completion_timeout(&nfc->completion,
>>>> +					 msecs_to_jiffies(timeout_ms)))
>>>> +		return -ETIMEDOUT;
>>>> +
>>>> +	if (need_cmd_read0) {
>>>> +		cmd = nfc->param.chip_select | NFC_CMD_CLE | NAND_CMD_READ0;
>>>> +		writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>> +		meson_nfc_drain_cmd(nfc);
>>>> +		meson_nfc_wait_cmd_finish(nfc, CMD_FIFO_EMPTY_TIMEOUT);
>>>> +	}  
>>>
>>> I forgot about this, you should avoid open coding core helpers, can you
>>> please send a followup patch to use nand_status_op() and
>>> nand_exit_status_op() ?  
>>
>> A ok, so:
>> 1) Sending NAND_CMD_STATUS goes to nand_status_op()
>> 2) Sending NAND_CMD_READ0 goes to nand_exit_status_op()
>>
>> Ok, no problem! I'll prepare and send it on this week!
> 
> Exactly. Sorry I had this in mind but I likely forgot to write it
> down.

Ok, got it!

Thanks, Arseniy

> 
> Thanks,
> Miquèl