On Mon, 2015-11-09 at 19:01 -0800, Brian Norris wrote:
> Hi Bayi,
>
> A few small comments.
>
> On Fri, Nov 06, 2015 at 11:48:08PM +0800, Bayi Cheng wrote:
> > add spi nor flash driver for mediatek controller
> >
> > Signed-off-by: Bayi Cheng <bayi.cheng@xxxxxxxxxxxx>
> > ---
> > drivers/mtd/spi-nor/Kconfig | 7 +
> > drivers/mtd/spi-nor/Makefile | 1 +
> > drivers/mtd/spi-nor/mtk-quadspi.c | 475 ++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 483 insertions(+)
> > create mode 100644 drivers/mtd/spi-nor/mtk-quadspi.c
>
>
> > diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
> > index e53333e..0bf3a7f8 100644
> > --- a/drivers/mtd/spi-nor/Makefile
> > +++ b/drivers/mtd/spi-nor/Makefile
> > @@ -1,3 +1,4 @@
> > obj-$(CONFIG_MTD_SPI_NOR) += spi-nor.o
> > obj-$(CONFIG_SPI_FSL_QUADSPI) += fsl-quadspi.o
> > +obj-$(CONFIG_MTD_MT81xx_NOR) += mtk-quadspi.o
> > obj-$(CONFIG_SPI_NXP_SPIFI) += nxp-spifi.o
> > diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c
> > new file mode 100644
> > index 0000000..6582811
> > --- /dev/null
> > +++ b/drivers/mtd/spi-nor/mtk-quadspi.c
> > @@ -0,0 +1,475 @@
>
> ...
>
> > +/* Can shift up to 48 bits (6 bytes) of TX/RX */
> > +#define MTK_NOR_MAX_SHIFT 6
>
> ...
>
> > +static int mt8173_nor_do_tx_rx(struct mt8173_nor *mt8173_nor, u8 op,
> > + u8 *tx, int txlen, u8 *rx, int rxlen)
> > +{
> > + int len = 1 + txlen + rxlen;
> > + int i, ret, idx;
> > +
> > + if (len > MTK_NOR_MAX_SHIFT + 1)
> > + return -EINVAL;
>
> So I see you adjusted these bounds to add 1, which inspired one of my
> questions on the cover letter.
>
> Why do you allow len=7, which means you'd program 7*8 to the COUNT
> register, when the SoC manual says it has a max of 48? Is the manual
> wrong?
>
Hi Brian, you are right, the manual is wrong here, Actually, it has a
max of 56. when we want to read 6 IDs, we need transfer 1 byte command
and 6 bytes null address to nor flash, then we can read the six IDs from
SHREGx register.
> I notice you added the '+ 1' to your driver, so it allows:
>
> do_tx_rx( txlen = 0 , rxlen = 6) /* e.g., for READ ID */
>
> but that means your driver also allows:
>
> do_tx_rx( txlen = 6, rxlen = 0) /* ERROR: this will allow out of
> bounds write on PRGDATA
> register -1 */
>
> If I understand correctly, the following constraints are more correct:
>
> /* Can only transmit 1 opcode and 5 other bytes */
> if (1 + txlen > MTK_NOR_MAX_SHIFT)
> return -EINVAL;
>
> /* Can only receive 6 bytes after the opcode */
> if (rxlen > MTK_NOR_MAX_SHIFT)
> return -EINVAL;
>
> /* Can only handle XXX bytes total */
> /* How many bytes is the max for register MTK_NOR_CNT_REG ? */
> if (len > XXX)
> return -EINVAL;
>
yes, your constraints seems more correct, and I will adapt these lines
to next patch.
> > +
> > + writeb(len * 8, mt8173_nor->base + MTK_NOR_CNT_REG);
> > +
> > + /* start at PRGDATA5, go down to PRGDATA0 */
> > + idx = MTK_NOR_MAX_SHIFT - 1;
> > +
> > + /* opcode */
> > + writeb(op, mt8173_nor->base + MTK_NOR_PRG_REG(idx));
> > + idx--;
> > +
> > + /* program TX data */
> > + for (i = 0; i < txlen; i++, idx--)
> > + writeb(tx[i], mt8173_nor->base + MTK_NOR_PRG_REG(idx));
> > +
> > + /* clear out rest of TX registers */
> > + while (idx >= 0) {
> > + writeb(0, mt8173_nor->base + MTK_NOR_PRG_REG(idx));
> > + idx--;
> > + }
> > +
> > + ret = mt8173_nor_execute_cmd(mt8173_nor, MTK_NOR_PRG_CMD);
> > + if (ret)
> > + return ret;
> > +
> > + /* restart at first RX byte */
> > + idx = rxlen - 1;
> > +
> > + /* read out RX data */
> > + for (i = 0; i < rxlen; i++, idx--)
> > + rx[i] = readb(mt8173_nor->base + MTK_NOR_SHREG(idx));
> > +
> > + return 0;
> > +}
> > +
>
> ...
>
> > +static int __init mtk_nor_init(struct mt8173_nor *mt8173_nor,
> > + struct device_node *flash_node)
> > +{
> > + struct mtd_part_parser_data ppdata = {
> > + .of_node = flash_node,
> > + };
> > + int ret;
> > + struct spi_nor *nor;
>
> Normally we'd have a blank line here.
>
Ok, I will fix it, and thanks for your advice.
> > + /* initialize controller to accept commands */
> > + writel(MTK_NOR_ENABLE_SF_CMD, mt8173_nor->base + MTK_NOR_WRPROT_REG);
> > +
> > + nor = &mt8173_nor->nor;
> > + nor->dev = mt8173_nor->dev;
> > + nor->priv = mt8173_nor;
> > + nor->flash_node = flash_node;
> > +
> > + /* fill the hooks to spi nor */
> > + nor->read = mt8173_nor_read;
> > + nor->read_reg = mt8173_nor_read_reg;
> > + nor->write = mt8173_nor_write;
> > + nor->write_reg = mt8173_nor_write_reg;
> > + nor->mtd.owner = THIS_MODULE;
> > + nor->mtd.name = "mtk_nor";
> > + /* initialized with NULL */
> > + ret = spi_nor_scan(nor, NULL, SPI_NOR_DUAL);
> > + if (ret)
> > + return ret;
> > +
> > + return mtd_device_parse_register(&nor->mtd, NULL, &ppdata, NULL, 0);
> > +}
>
> ...
>
> Brian
>
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