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Date: Mon, 6 May 2024 15:53:22 +0200
From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Arseniy Krasnov <avkrasnov@salutedevices.com>
Cc: Richard Weinberger <richard@nod.at>, Vignesh Raghavendra
 <vigneshr@ti.com>, Rob Herring <robh+dt@kernel.org>, Krzysztof Kozlowski
 <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>,
 Neil Armstrong <neil.armstrong@linaro.org>, Kevin Hilman
 <khilman@baylibre.com>, Jerome Brunet <jbrunet@baylibre.com>, Martin
 Blumenstingl <martin.blumenstingl@googlemail.com>,
 <linux-mtd@lists.infradead.org>, <devicetree@vger.kernel.org>,
 <linux-arm-kernel@lists.infradead.org>,
 <linux-amlogic@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
 <oxffffaa@gmail.com>, <kernel@sberdevices.ru>
Subject: Re: [PATCH v5 2/2] mtd: rawnand: meson: support R/W mode for boot
 ROM
Message-ID: <20240506155322.002346d0@xps-13>
In-Reply-To: <20240416085101.740458-3-avkrasnov@salutedevices.com>
References: <20240416085101.740458-1-avkrasnov@salutedevices.com>
	<20240416085101.740458-3-avkrasnov@salutedevices.com>
Organization: Bootlin
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Hi Arseniy,

avkrasnov@salutedevices.com wrote on Tue, 16 Apr 2024 11:51:01 +0300:

> Boot ROM code on Meson requires that some pages on NAND must be written
> in special mode: "short" ECC mode where each block is 384 bytes and
> scrambling mode is on. Such pages located with the specified interval
> within specified offset. Both interval and offset are located in the
> device tree and used by driver if 'nand-is-boot-medium' is set for
> NAND chip.
>=20
> Signed-off-by: Arseniy Krasnov <avkrasnov@salutedevices.com>
> ---
>  drivers/mtd/nand/raw/meson_nand.c | 88 +++++++++++++++++++++----------
>  1 file changed, 59 insertions(+), 29 deletions(-)
>=20
> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/mes=
on_nand.c
> index 00ce0e5bb970..9ee11243b257 100644
> --- a/drivers/mtd/nand/raw/meson_nand.c
> +++ b/drivers/mtd/nand/raw/meson_nand.c
> @@ -35,6 +35,7 @@
>  #define NFC_CMD_RB		BIT(20)
>  #define NFC_CMD_SCRAMBLER_ENABLE	BIT(19)
>  #define NFC_CMD_SCRAMBLER_DISABLE	0
> +#define NFC_CMD_SHORTMODE_ENABLE	1
>  #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))
> @@ -78,6 +79,8 @@
>  #define DMA_DIR(dir)		((dir) ? NFC_CMD_N2M : NFC_CMD_M2N)
>  #define DMA_ADDR_ALIGN		8
> =20
> +#define NFC_SHORT_MODE_ECC_SZ	384
> +
>  #define ECC_CHECK_RETURN_FF	(-1)
> =20
>  #define NAND_CE0		(0xe << 10)
> @@ -125,6 +128,8 @@ struct meson_nfc_nand_chip {
>  	u32 twb;
>  	u32 tadl;
>  	u32 tbers_max;
> +	u32 boot_pages;
> +	u32 boot_page_step;
> =20
>  	u32 bch_mode;
>  	u8 *data_buf;
> @@ -298,28 +303,49 @@ static void meson_nfc_cmd_seed(struct meson_nfc *nf=
c, u32 seed)
>  	       nfc->reg_base + NFC_REG_CMD);
>  }
> =20
> -static void meson_nfc_cmd_access(struct nand_chip *nand, int raw, bool d=
ir,
> -				 int scrambler)
> +static int meson_nfc_page_is_boot(struct nand_chip *nand, int page)

meson_nfc_is_boot_page() is easier to read

> +{
> +	const struct meson_nfc_nand_chip *meson_chip =3D to_meson_nand(nand);
> +
> +	return (nand->options & NAND_IS_BOOT_MEDIUM) &&
> +	       !(page % meson_chip->boot_page_step) &&

I would dedicate all the space below ->boot_pages to the bootrom, no?
Using space in between sounds silly.

> +	       (page < meson_chip->boot_pages);
> +}
> +
> +static void meson_nfc_cmd_access(struct nand_chip *nand, bool raw, bool =
dir, int page)
>  {
> +	const struct meson_nfc_nand_chip *meson_chip =3D to_meson_nand(nand);
>  	struct mtd_info *mtd =3D nand_to_mtd(nand);
>  	struct meson_nfc *nfc =3D nand_get_controller_data(mtd_to_nand(mtd));
> -	struct meson_nfc_nand_chip *meson_chip =3D to_meson_nand(nand);
> -	u32 bch =3D meson_chip->bch_mode, cmd;
>  	int len =3D mtd->writesize, pagesize, pages;
> +	int scrambler;
> +	u32 cmd;
> =20
> -	pagesize =3D nand->ecc.size;
> +	if (nand->options & NAND_NEED_SCRAMBLING)
> +		scrambler =3D NFC_CMD_SCRAMBLER_ENABLE;
> +	else
> +		scrambler =3D NFC_CMD_SCRAMBLER_DISABLE;

That is a separate feature?

> =20
>  	if (raw) {
>  		len =3D mtd->writesize + mtd->oobsize;
>  		cmd =3D len | scrambler | DMA_DIR(dir);
> -		writel(cmd, nfc->reg_base + NFC_REG_CMD);
> -		return;
> -	}
> +	} else if (meson_nfc_page_is_boot(nand, page)) {
> +		pagesize =3D NFC_SHORT_MODE_ECC_SZ >> 3;
> +		pages =3D mtd->writesize / 512;
> +
> +		scrambler =3D NFC_CMD_SCRAMBLER_ENABLE;
> +		cmd =3D CMDRWGEN(DMA_DIR(dir), scrambler, NFC_ECC_BCH8_1K,
> +			       NFC_CMD_SHORTMODE_ENABLE, pagesize, pages);
> +	} else {
> +		pagesize =3D nand->ecc.size >> 3;
> +		pages =3D len / nand->ecc.size;
> =20
> -	pages =3D len / nand->ecc.size;
> +		cmd =3D CMDRWGEN(DMA_DIR(dir), scrambler, meson_chip->bch_mode,
> +			       NFC_CMD_SHORTMODE_DISABLE, pagesize, pages);
> +	}
> =20
> -	cmd =3D CMDRWGEN(DMA_DIR(dir), scrambler, bch,
> -		       NFC_CMD_SHORTMODE_DISABLE, pagesize, pages);
> +	if (scrambler =3D=3D NFC_CMD_SCRAMBLER_ENABLE)
> +		meson_nfc_cmd_seed(nfc, page);
> =20
>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  }
> @@ -743,15 +769,7 @@ static int meson_nfc_write_page_sub(struct nand_chip=
 *nand,
>  	if (ret)
>  		return ret;
> =20
> -	if (nand->options & NAND_NEED_SCRAMBLING) {
> -		meson_nfc_cmd_seed(nfc, page);
> -		meson_nfc_cmd_access(nand, raw, DIRWRITE,
> -				     NFC_CMD_SCRAMBLER_ENABLE);
> -	} else {
> -		meson_nfc_cmd_access(nand, raw, DIRWRITE,
> -				     NFC_CMD_SCRAMBLER_DISABLE);
> -	}
> -

Ok I get it, the feature already exist but is handled differently.
Please split this patch:
- improve scrambler handling to facilitate boot page support
- add boot pages support

> +	meson_nfc_cmd_access(nand, raw, DIRWRITE, page);
>  	cmd =3D nfc->param.chip_select | NFC_CMD_CLE | NAND_CMD_PAGEPROG;
>  	writel(cmd, nfc->reg_base + NFC_REG_CMD);
>  	meson_nfc_queue_rb(nand, PSEC_TO_MSEC(sdr->tPROG_max), false);
> @@ -829,15 +847,7 @@ static int meson_nfc_read_page_sub(struct nand_chip =
*nand,
>  	if (ret)
>  		return ret;
> =20
> -	if (nand->options & NAND_NEED_SCRAMBLING) {
> -		meson_nfc_cmd_seed(nfc, page);
> -		meson_nfc_cmd_access(nand, raw, DIRREAD,
> -				     NFC_CMD_SCRAMBLER_ENABLE);
> -	} else {
> -		meson_nfc_cmd_access(nand, raw, DIRREAD,
> -				     NFC_CMD_SCRAMBLER_DISABLE);
> -	}
> -
> +	meson_nfc_cmd_access(nand, raw, DIRREAD, page);
>  	ret =3D meson_nfc_wait_dma_finish(nfc);
>  	meson_nfc_check_ecc_pages_valid(nfc, nand, raw);
> =20
> @@ -1436,6 +1446,26 @@ meson_nfc_nand_chip_init(struct device *dev,
>  	if (ret)
>  		return ret;
> =20
> +	if (nand->options & NAND_IS_BOOT_MEDIUM) {
> +		ret =3D of_property_read_u32(np, "amlogic,boot-pages",
> +					   &meson_chip->boot_pages);
> +		if (ret) {
> +			dev_err(dev, "could not retrieve 'amlogic,boot-pages' property: %d",
> +				ret);
> +			nand_cleanup(nand);
> +			return ret;
> +		}
> +
> +		ret =3D of_property_read_u32(np, "amlogic,boot-page-step",
> +					   &meson_chip->boot_page_step);
> +		if (ret) {
> +			dev_err(dev, "could not retrieve 'amlogic,boot-page-step' property: %=
d",
> +				ret);
> +			nand_cleanup(nand);
> +			return ret;
> +		}
> +	}
> +
>  	ret =3D mtd_device_register(mtd, NULL, 0);
>  	if (ret) {
>  		dev_err(dev, "failed to register MTD device: %d\n", ret);


Thanks,
Miqu=C3=A8l