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Message-ID: <20220103111423.5c2b72c9@collabora.com>
Date: Mon, 3 Jan 2022 11:14:23 +0100
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Apurva Nandan <a-nandan@...com>
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
Richard Weinberger <richard@....at>,
Vignesh Raghavendra <vigneshr@...com>,
Mark Brown <broonie@...nel.org>,
Patrice Chotard <patrice.chotard@...s.st.com>,
Christophe Kerello <christophe.kerello@...s.st.com>,
Daniel Palmer <daniel@...f.com>,
Alexander Lobakin <alobakin@...me>,
<linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<linux-spi@...r.kernel.org>, <p.yadav@...com>
Subject: Re: [PATCH v3 11/17] mtd: spinand: Allow enabling/disabling Octal
DTR mode in the core
On Sat, 1 Jan 2022 13:12:44 +0530
Apurva Nandan <a-nandan@...com> wrote:
> Enable Octal DTR SPI mode, i.e. 8D-8D-8D mode, if the SPI NAND flash
> device supports it. Mixed OSPI (1S-1S-8S & 1S-8S-8S), mixed DTR modes
> (1S-1D-8D), etc. aren't supported yet.
>
> The method to switch to Octal DTR SPI mode may vary across
> manufacturers. For example, for Winbond, it is enabled by writing
> values to the volatile configuration register. So, let the
> manufacturer's code have their own implementation for switching to
> Octal DTR SPI mode.
>
> Check for the SPI NAND device's support for Octal DTR mode using
> spinand flags, and if the data_ops and ctrl_ops are 8D-8D-8D, call
> change_mode() manufacturer op. If the SPI controller doesn't
> supports these modes, the selected data_ops and ctrl_ops will
> prevent switching to the Octal DTR mode. And finally update the
> spinand protocol and ctrl_ops on success. Similarly, for disabling
> Octal DTR mode, call change_mode(), and update protocol and ctrl_ops.
>
> Signed-off-by: Apurva Nandan <a-nandan@...com>
> ---
> drivers/mtd/nand/spi/core.c | 79 +++++++++++++++++++++++++++++++++++++
> include/linux/mtd/spinand.h | 1 +
> 2 files changed, 80 insertions(+)
>
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 1a602e4dd6bd..2fd08085db6f 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1067,6 +1067,81 @@ spinand_select_ctrl_ops_variant(struct spinand_device *spinand,
> return NULL;
> }
>
> +static bool spinand_op_is_octal_dtr(const struct spi_mem_op *op)
> +{
> + return op->cmd.buswidth == 8 && op->cmd.dtr &&
> + op->addr.buswidth == 8 && op->addr.dtr &&
> + op->data.buswidth == 8 && op->data.dtr;
> +}
> +
> +static int spinand_init_octal_dtr_enable(struct spinand_device *spinand)
> +{
> + struct device *dev = &spinand->spimem->spi->dev;
> + const struct spinand_ctrl_ops *octal_dtr_ctrl_ops;
> + int ret;
> +
> + if (!(spinand->flags & SPINAND_HAS_OCTAL_DTR_BIT))
> + return 0;
> +
> + if (!(spinand_op_is_octal_dtr(spinand->data_ops.read_cache) &&
> + spinand_op_is_octal_dtr(spinand->data_ops.write_cache) &&
> + spinand_op_is_octal_dtr(spinand->data_ops.update_cache)))
> + return 0;
> +
> + octal_dtr_ctrl_ops = spinand_select_ctrl_ops_variant(spinand,
> + spinand->desc_entry->ctrl_ops_variants,
> + SPINAND_8D_8D_8D);
> +
> + if (!octal_dtr_ctrl_ops)
> + return 0;
> +
> + if (!spinand->manufacturer->ops->change_mode) {
> + dev_dbg(dev,
> + "Missing ->change_mode(), unable to switch mode\n");
> + return -EINVAL;
Looks like something that's worth printing at the info level, and I
think returning EOPNOTSUPP would be more appropriate.
> + }
> +
> + ret = spinand->manufacturer->ops->change_mode(spinand,
> + SPINAND_8D_8D_8D);
> + if (ret) {
> + dev_err(dev,
> + "Failed to enable Octal DTR SPI mode (err = %d)\n",
> + ret);
> + return ret;
> + }
> +
> + spinand->protocol = SPINAND_8D_8D_8D;
> + spinand->ctrl_ops = octal_dtr_ctrl_ops;
> +
> + dev_dbg(dev,
> + "%s SPI NAND switched to Octal DTR SPI (8D-8D-8D) mode\n",
> + spinand->manufacturer->name);
> + return 0;
> +}
> +
> +static int spinand_init_octal_dtr_disable(struct spinand_device *spinand)
This function is never used. I guess it should be called in the
suspend/shutdown path, at least.
> +{
> + struct device *dev = &spinand->spimem->spi->dev;
> + int ret;
> +
> + if (!spinand->manufacturer->ops->change_mode)
> + return -EINVAL;
> +
> + ret = spinand->manufacturer->ops->change_mode(spinand,
> + SPINAND_1S_1S_1S);
> +
> + if (ret) {
> + dev_err(dev,
> + "Failed to disable Octal DTR SPI mode (err = %d)\n",
> + ret);
> + return ret;
> + }
> +
> + spinand->protocol = SPINAND_1S_1S_1S;
> + spinand->ctrl_ops = &spinand_default_ctrl_ops;
> + return 0;
> +}
> +
> /**
> * spinand_match_and_init() - Try to find a match between a device ID and an
> * entry in a spinand_info table
> @@ -1203,6 +1278,10 @@ static int spinand_init_flash(struct spinand_device *spinand)
> break;
> }
>
> + ret = spinand_init_octal_dtr_enable(spinand);
> + if (ret)
> + return ret;
> +
> if (ret)
> spinand_manufacturer_cleanup(spinand);
>
> diff --git a/include/linux/mtd/spinand.h b/include/linux/mtd/spinand.h
> index a8c071983a27..f12aa4516fab 100644
> --- a/include/linux/mtd/spinand.h
> +++ b/include/linux/mtd/spinand.h
> @@ -417,6 +417,7 @@ struct spinand_ecc_info {
>
> #define SPINAND_HAS_QE_BIT BIT(0)
> #define SPINAND_HAS_CR_FEAT_BIT BIT(1)
> +#define SPINAND_HAS_OCTAL_DTR_BIT BIT(2)
Do we really need a new flag for this? Isn't the template op
initialization enough to reflect whether the NAND and controller can do
8DTR or not?
>
> /**
> * struct spinand_ondie_ecc_conf - private SPI-NAND on-die ECC engine structure
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