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Message-ID: <20230607175056.6f1ec38e@xps-13>
Date: Wed, 7 Jun 2023 17:50:56 +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>,
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 v1 2/2] mtd: rawnand: meson: waiting w/o wired
ready/busy pin
Hi Arseniy,
AVKrasnov@...rdevices.ru wrote on Wed, 7 Jun 2023 17:50:25 +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 | 82 +++++++++++++++++++++++++++++--
> 1 file changed, 78 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> index 074e14225c06..935de8e4934d 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);
> + }
> +
> + 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;
>
> nsels = of_property_count_elems_of_size(np, "reg", sizeof(u32));
> if (!nsels || nsels > MAX_CE_NUM) {
> @@ -1287,6 +1347,20 @@ 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) {
> + /* If property was not found, don't use rb pin. */
> + if (ret == -EINVAL)
> + nfc->no_rb_pin = true;
> + else
> + return -EINVAL;
You must propagate the real error code, so return ret here.
> + } else {
> + if (nand_rb_val)
> + return -EINVAL;
> +
> + nfc->no_rb_pin = false;
I expect nfc structure to be allocated with kzalloc, if that's the
case, then you don't need this line. Actually if you reset nand_rb_val
at creation time you could have something more readable, like:
ret = of_prop(...)
if (ret == -EINVAL)
no_rb_pin = true;
else if (ret)
return ret;
if (nand_rb_val)
return -EINVAL;
Otherwise both patches look good to me.
> + }
> +
> ret = nand_scan(nand, nsels);
> if (ret)
> return ret;
Thanks,
Miquèl
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