Re: [PATCH v10 02/17] spi: spi-mem: allow specifying a command's extension

From: <Tudor.Ambarus@microchip.com>
To: <p.yadav@ti.com>, <miquel.raynal@bootlin.com>, <richard@nod.at>,
	<vigneshr@ti.com>, <broonie@kernel.org>,
	<Nicolas.Ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
	<Ludovic.Desroches@microchip.com>, <matthias.bgg@gmail.com>,
	<michal.simek@xilinx.com>, <linux-mtd@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <linux-spi@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-mediatek@lists.infradead.org>
Cc: <nsekhar@ti.com>, <boris.brezillon@collabora.com>
Subject: Re: [PATCH v10 02/17] spi: spi-mem: allow specifying a command's extension
Date: Mon, 13 Jul 2020 06:15:32 +0000	[thread overview]
Message-ID: <0e7ce8fc-b3aa-b93a-d717-fce968686bb3@microchip.com> (raw)
In-Reply-To: <20200623183030.26591-3-p.yadav@ti.com>

On 6/23/20 9:30 PM, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> In xSPI mode, flashes expect 2-byte opcodes. The second byte is called
> the "command extension". There can be 3 types of extensions in xSPI:
> repeat, invert, and hex. When the extension type is "repeat", the same
> opcode is sent twice. When it is "invert", the second byte is the
> inverse of the opcode. When it is "hex" an additional opcode byte based
> is sent with the command whose value can be anything.
> 
> So, make opcode a 16-bit value and add a 'nbytes', similar to how
> multiple address widths are handled.
> 
> Some places use sizeof(op->cmd.opcode). Replace them with op->cmd.nbytes
> 
> The spi-mxic and spi-zynq-qspi drivers directly use op->cmd.opcode as a
> buffer. Now that opcode is a 2-byte field, this can result in different
> behaviour depending on if the machine is little endian or big endian.
> Extract the opcode in a local 1-byte variable and use that as the buffer
> instead. Both these drivers would reject multi-byte opcodes in their
> supports_op() hook anyway, so we only need to worry about single-byte
> opcodes for now.
> 
> The above two changes are put in this commit to keep the series
> bisectable.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> ---
>  drivers/spi/spi-mem.c       | 13 +++++++------
>  drivers/spi/spi-mtk-nor.c   |  4 ++--
>  drivers/spi/spi-mxic.c      |  3 ++-
>  drivers/spi/spi-zynq-qspi.c | 11 ++++++-----
>  include/linux/spi/spi-mem.h |  6 +++++-
>  5 files changed, 22 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index 93e255287ab9..ef53290b7d24 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -159,6 +159,9 @@ bool spi_mem_default_supports_op(struct spi_mem *mem,
>         if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
>                 return false;
> 
> +       if (op->cmd.nbytes != 1)
> +               return false;

I would put this imediately before:

if (spi_check_buswidth_req(mem, op->cmd.buswidth, true))  

to speed up the exit and avoid the rest of the checks that would
become superflous.

> +
>         return true;
>  }
>  EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
> @@ -173,7 +176,7 @@ static bool spi_mem_buswidth_is_valid(u8 buswidth)
> 
>  static int spi_mem_check_op(const struct spi_mem_op *op)
>  {
> -       if (!op->cmd.buswidth)
> +       if (!op->cmd.buswidth || !op->cmd.nbytes)

we would be more explicit with:
if (!op->cmd.buswidth || !op->cmd.nbytes || op->cmd.nbytes > 2)

With these addressed:

Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>

>                 return -EINVAL;
> 
>         if ((op->addr.nbytes && !op->addr.buswidth) ||
> @@ -309,8 +312,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>                         return ret;
>         }
> 
> -       tmpbufsize = sizeof(op->cmd.opcode) + op->addr.nbytes +
> -                    op->dummy.nbytes;
> +       tmpbufsize = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
> 
>         /*
>          * Allocate a buffer to transmit the CMD, ADDR cycles with kmalloc() so
> @@ -325,7 +327,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> 
>         tmpbuf[0] = op->cmd.opcode;
>         xfers[xferpos].tx_buf = tmpbuf;
> -       xfers[xferpos].len = sizeof(op->cmd.opcode);
> +       xfers[xferpos].len = op->cmd.nbytes;
>         xfers[xferpos].tx_nbits = op->cmd.buswidth;
>         spi_message_add_tail(&xfers[xferpos], &msg);
>         xferpos++;
> @@ -427,8 +429,7 @@ int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
>                 return ctlr->mem_ops->adjust_op_size(mem, op);
> 
>         if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op) {
> -               len = sizeof(op->cmd.opcode) + op->addr.nbytes +
> -                     op->dummy.nbytes;
> +               len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
> 
>                 if (len > spi_max_transfer_size(mem->spi))
>                         return -EINVAL;
> diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
> index 7bc302b50396..d5f393871619 100644
> --- a/drivers/spi/spi-mtk-nor.c
> +++ b/drivers/spi/spi-mtk-nor.c
> @@ -195,7 +195,7 @@ static int mtk_nor_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
>                 }
>         }
> 
> -       len = MTK_NOR_PRG_MAX_SIZE - sizeof(op->cmd.opcode) - op->addr.nbytes -
> +       len = MTK_NOR_PRG_MAX_SIZE - op->cmd.nbytes - op->addr.nbytes -
>               op->dummy.nbytes;
>         if (op->data.nbytes > len)
>                 op->data.nbytes = len;
> @@ -219,7 +219,7 @@ static bool mtk_nor_supports_op(struct spi_mem *mem,
>                                (op->dummy.buswidth == 0) &&
>                                (op->data.buswidth == 1);
>         }
> -       len = sizeof(op->cmd.opcode) + op->addr.nbytes + op->dummy.nbytes;
> +       len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
>         if ((len > MTK_NOR_PRG_MAX_SIZE) ||
>             ((op->data.nbytes) && (len == MTK_NOR_PRG_MAX_SIZE)))
>                 return false;
> diff --git a/drivers/spi/spi-mxic.c b/drivers/spi/spi-mxic.c
> index 69491f3a515d..8c630acb0110 100644
> --- a/drivers/spi/spi-mxic.c
> +++ b/drivers/spi/spi-mxic.c
> @@ -356,6 +356,7 @@ static int mxic_spi_mem_exec_op(struct spi_mem *mem,
>         int nio = 1, i, ret;
>         u32 ss_ctrl;
>         u8 addr[8];
> +       u8 opcode = op->cmd.opcode;
> 
>         ret = mxic_spi_set_freq(mxic, mem->spi->max_speed_hz);
>         if (ret)
> @@ -393,7 +394,7 @@ static int mxic_spi_mem_exec_op(struct spi_mem *mem,
>         writel(readl(mxic->regs + HC_CFG) | HC_CFG_MAN_CS_ASSERT,
>                mxic->regs + HC_CFG);
> 
> -       ret = mxic_spi_data_xfer(mxic, &op->cmd.opcode, NULL, 1);
> +       ret = mxic_spi_data_xfer(mxic, &opcode, NULL, 1);
>         if (ret)
>                 goto out;
> 
> diff --git a/drivers/spi/spi-zynq-qspi.c b/drivers/spi/spi-zynq-qspi.c
> index 17641157354d..bbf3d90561f5 100644
> --- a/drivers/spi/spi-zynq-qspi.c
> +++ b/drivers/spi/spi-zynq-qspi.c
> @@ -527,20 +527,21 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
>         struct zynq_qspi *xqspi = spi_controller_get_devdata(mem->spi->master);
>         int err = 0, i;
>         u8 *tmpbuf;
> +       u8 opcode = op->cmd.opcode;
> 
>         dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
> -               op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
> +               opcode, op->cmd.buswidth, op->addr.buswidth,
>                 op->dummy.buswidth, op->data.buswidth);
> 
>         zynq_qspi_chipselect(mem->spi, true);
>         zynq_qspi_config_op(xqspi, mem->spi);
> 
> -       if (op->cmd.opcode) {
> +       if (op->cmd.nbytes) {
>                 reinit_completion(&xqspi->data_completion);
> -               xqspi->txbuf = (u8 *)&op->cmd.opcode;
> +               xqspi->txbuf = &opcode;
>                 xqspi->rxbuf = NULL;
> -               xqspi->tx_bytes = sizeof(op->cmd.opcode);
> -               xqspi->rx_bytes = sizeof(op->cmd.opcode);
> +               xqspi->tx_bytes = op->cmd.nbytes;
> +               xqspi->rx_bytes = op->cmd.nbytes;
>                 zynq_qspi_write_op(xqspi, ZYNQ_QSPI_FIFO_DEPTH, true);
>                 zynq_qspi_write(xqspi, ZYNQ_QSPI_IEN_OFFSET,
>                                 ZYNQ_QSPI_IXR_RXTX_MASK);
> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
> index e3dcb956bf61..159463cc659c 100644
> --- a/include/linux/spi/spi-mem.h
> +++ b/include/linux/spi/spi-mem.h
> @@ -17,6 +17,7 @@
>         {                                                       \
>                 .buswidth = __buswidth,                         \
>                 .opcode = __opcode,                             \
> +               .nbytes = 1,                                    \
>         }
> 
>  #define SPI_MEM_OP_ADDR(__nbytes, __val, __buswidth)           \
> @@ -69,6 +70,8 @@ enum spi_mem_data_dir {
> 
>  /**
>   * struct spi_mem_op - describes a SPI memory operation
> + * @cmd.nbytes: number of opcode bytes (only 1 or 2 are valid). The opcode is
> + *             sent MSB-first.
>   * @cmd.buswidth: number of IO lines used to transmit the command
>   * @cmd.opcode: operation opcode
>   * @cmd.dtr: whether the command opcode should be sent in DTR mode or not
> @@ -94,9 +97,10 @@ enum spi_mem_data_dir {
>   */
>  struct spi_mem_op {
>         struct {
> +               u8 nbytes;
>                 u8 buswidth;
>                 u8 dtr : 1;
> -               u8 opcode;
> +               u16 opcode;
>         } cmd;
> 
>         struct {
> --
> 2.27.0
> 