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Message-ID: <20230607100257.627fc438@xps-13>
Date: Wed, 7 Jun 2023 10:02:57 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
Cc: Liang Yang <liang.yang@...ogic.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
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>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-amlogic@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mtd: rawnand: meson: waiting w/o wired ready/busy
pin
Hi Arseniy,
AVKrasnov@...rdevices.ru wrote on Wed, 7 Jun 2023 10:30:15 +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>
> ---
> Changelog:
> v1 -> v2:
> * Remove small delays from 'meson_nfc_wait_no_rb_pin()'. Both have no
> effect according Liang's message.
> * Type of 'no_rb_pin' is u32, the same as for 'nand-rb' property.
> * 'meson_nfc_wait_no_rb_pin()' doesn't send NAND_CMD_READ0 in case of
> page programming. Extra argument is added to 'meson_nfc_queue_rb()'
> to check that case.
>
> drivers/mtd/nand/raw/meson_nand.c | 74 +++++++++++++++++++++++++++++--
> 1 file changed, 70 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index 074e14225c06..ae404655b68c 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;
> + u32 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);
> + }
> +
> + return 0;
> +}
> +
> +static int meson_nfc_wait_rb_pin(struct meson_nfc *nfc, int timeout_ms)
> {
> u32 cmd, cfg;
> int ret = 0;
> @@ -420,6 +457,25 @@ 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.
Please also tell us in which case this is needed/not needed.
> + */
> + 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 +679,7 @@ 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 +725,7 @@ 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 +1008,8 @@ 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;
> @@ -1412,6 +1469,15 @@ static int meson_nfc_probe(struct platform_device *pdev)
> return ret;
> }
>
> + ret = of_property_read_u32(dev->of_node, "nand-rb", &nfc->no_rb_pin);
> + if (ret) {
> + /* If property was not found, don't use rb pin. */
> + if (ret == -EINVAL)
> + nfc->no_rb_pin = 1;
You mix two things:
- the presence of the RB pin
- the RB line
Just turn no_rb_pin into a boolean but d'ont use it to read the
property. Use another local u32 and just check the value is 0. If the
value is not 0, then return -EINVAL.
Also you should constrain the dt property in the binding to be either
absent or 0 but nothing else, with something like:
maxItems: 1
minimum: 0
maximum: 0
> + else
> + return ret;
> + }
> +
> writel(0, nfc->reg_base + NFC_REG_CFG);
> ret = devm_request_irq(dev, irq, meson_nfc_irq, 0, dev_name(dev), nfc);
> if (ret) {
Thanks,
Miquèl
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