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

[Arseniy Krasnov <avkrasnov@sberdevices.ru>]

On 04.07.2023 15:43, Miquel Raynal wrote:
> Hi Arseniy,
> 
> AVKrasnov@sberdevices.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@amlogic.com>
>> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.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!

Thanks, Arseniy

> 
>> +
>> +	return 0;
>> +}
>> +
>> +static int meson_nfc_wait_rb_pin(struct meson_nfc *nfc, int timeout_ms)
>>  {
>>  	u32 cmd, cfg;
>>  	int ret = 0;
>> @@ -420,6 +457,27 @@ static int meson_nfc_queue_rb(struct meson_nfc *nfc, int timeout_ms)
>>  	return ret;
>>  }
>>  
>> +static int meson_nfc_queue_rb(struct meson_nfc *nfc, int timeout_ms,
>> +			      bool need_cmd_read0)
>> +{
>> +	if (nfc->no_rb_pin) {
>> +		/* This mode is used when there is no wired R/B pin.
>> +		 * It works like 'nand_soft_waitrdy()', but instead of
>> +		 * polling NAND_CMD_STATUS bit in the software loop,
>> +		 * it will wait for interrupt - controllers checks IO
>> +		 * bus and when it detects NAND_CMD_STATUS on it, it
>> +		 * raises interrupt. After interrupt, NAND_CMD_READ0 is
>> +		 * sent as terminator of the ready waiting procedure if
>> +		 * needed (for all cases except page programming - this
>> +		 * is reason of 'need_cmd_read0' flag).
>> +		 */
>> +		return meson_nfc_wait_no_rb_pin(nfc, timeout_ms,
>> +						need_cmd_read0);
>> +	} else {
>> +		return meson_nfc_wait_rb_pin(nfc, timeout_ms);
>> +	}
>> +}
>> +
>>  static void meson_nfc_set_user_byte(struct nand_chip *nand, u8 *oob_buf)
>>  {
>>  	struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
>> @@ -623,7 +681,7 @@ static int meson_nfc_rw_cmd_prepare_and_execute(struct nand_chip *nand,
>>  	if (in) {
>>  		nfc->cmdfifo.rw.cmd1 = cs | NFC_CMD_CLE | NAND_CMD_READSTART;
>>  		writel(nfc->cmdfifo.rw.cmd1, nfc->reg_base + NFC_REG_CMD);
>> -		meson_nfc_queue_rb(nfc, PSEC_TO_MSEC(sdr->tR_max));
>> +		meson_nfc_queue_rb(nfc, PSEC_TO_MSEC(sdr->tR_max), true);
>>  	} else {
>>  		meson_nfc_cmd_idle(nfc, nfc->timing.tadl);
>>  	}
>> @@ -669,7 +727,7 @@ static int meson_nfc_write_page_sub(struct nand_chip *nand,
>>  
>>  	cmd = nfc->param.chip_select | NFC_CMD_CLE | NAND_CMD_PAGEPROG;
>>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>> -	meson_nfc_queue_rb(nfc, PSEC_TO_MSEC(sdr->tPROG_max));
>> +	meson_nfc_queue_rb(nfc, PSEC_TO_MSEC(sdr->tPROG_max), false);
>>  
>>  	meson_nfc_dma_buffer_release(nand, data_len, info_len, DMA_TO_DEVICE);
>>  
>> @@ -952,7 +1010,8 @@ static int meson_nfc_exec_op(struct nand_chip *nand,
>>  			break;
>>  
>>  		case NAND_OP_WAITRDY_INSTR:
>> -			meson_nfc_queue_rb(nfc, instr->ctx.waitrdy.timeout_ms);
>> +			meson_nfc_queue_rb(nfc, instr->ctx.waitrdy.timeout_ms,
>> +					   true);
>>  			if (instr->delay_ns)
>>  				meson_nfc_cmd_idle(nfc, delay_idle);
>>  			break;
>> @@ -1248,6 +1307,7 @@ meson_nfc_nand_chip_init(struct device *dev,
>>  	struct mtd_info *mtd;
>>  	int ret, i;
>>  	u32 tmp, nsels;
>> +	u32 nand_rb_val = 0;
>>  
>>  	nsels = of_property_count_elems_of_size(np, "reg", sizeof(u32));
>>  	if (!nsels || nsels > MAX_CE_NUM) {
>> @@ -1287,6 +1347,15 @@ meson_nfc_nand_chip_init(struct device *dev,
>>  	mtd->owner = THIS_MODULE;
>>  	mtd->dev.parent = dev;
>>  
>> +	ret = of_property_read_u32(np, "nand-rb", &nand_rb_val);
>> +	if (ret == -EINVAL)
>> +		nfc->no_rb_pin = true;
>> +	else if (ret)
>> +		return ret;
>> +
>> +	if (nand_rb_val)
>> +		return -EINVAL;
>> +
>>  	ret = nand_scan(nand, nsels);
>>  	if (ret)
>>  		return ret;
> 
> 
> Thanks,
> Miquèl

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