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Subject[PATCH 1/3] spi: spi-mtk-nor: make use of full capability of prg mode
Date
"program" mode on this controller can trigger up to 56 bits of data
shifting. During the operation, data in PRGDATA[0-5] will be
shifted out from MOSI, and data from MISO will be continuously filling
SHREG[0-9].
Currently this mode is used to implement transfer_one_message for 6-byte
full-duplex transfer, but it can execute a transfer for up-to 7 bytes
as long as the last byte is read only.
transfer_one_message is expected to perform full-duplex transfer,
instead of transfer with specific format. mtk_nor_spi_mem_prg is
added here to use this extra byte.

Newer version of this controller can trigger longer data shifting with
shift bytes more than PRGDATA_MAX + SHREG_MAX. This patch is implemented
with that in mind and it checks against both SHREG_MAX and PRG_CNT_MAX
for future support of new controllers.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
---
There are two calls of mtk_nor_spi_mem_prg in mtk_nor_exec_op,
which doesn't look great. But I'd prefer keeping it this way
to minimize change of mtk_nor_exec_op.
I'll follow up with a cleanup patchset after this one gets
merged.

drivers/spi/spi-mtk-nor.c | 82 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 80 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
index 62f5ff2779884..a0087a5e869b9 100644
--- a/drivers/spi/spi-mtk-nor.c
+++ b/drivers/spi/spi-mtk-nor.c
@@ -27,6 +27,7 @@
#define MTK_NOR_CMD_MASK GENMASK(5, 0)

#define MTK_NOR_REG_PRG_CNT 0x04
+#define MTK_NOR_PRG_CNT_MAX 56
#define MTK_NOR_REG_RDATA 0x0c

#define MTK_NOR_REG_RADR0 0x10
@@ -404,6 +405,83 @@ static int mtk_nor_pp_unbuffered(struct mtk_nor *sp,
return mtk_nor_cmd_exec(sp, MTK_NOR_CMD_WRITE, 6 * BITS_PER_BYTE);
}

+static int mtk_nor_spi_mem_prg(struct mtk_nor *sp, const struct spi_mem_op *op)
+{
+ int rx_len = 0;
+ int reg_offset = MTK_NOR_REG_PRGDATA_MAX;
+ int tx_len, prg_len;
+ int i, ret;
+ void __iomem *reg;
+ u8 bufbyte;
+
+ tx_len = op->cmd.nbytes + op->addr.nbytes;
+
+ // count dummy bytes only if we need to write data after it
+ if (op->data.dir == SPI_MEM_DATA_OUT)
+ tx_len += op->dummy.nbytes + op->data.nbytes;
+ else if (op->data.dir == SPI_MEM_DATA_IN)
+ rx_len = op->data.nbytes;
+
+ prg_len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes +
+ op->data.nbytes;
+
+ // an invalid op may reach here if the caller calls exec_op without
+ // adjust_op_size. return -EINVAL instead of -ENOTSUPP so that
+ // spi-mem won't try this op again with generic spi transfers.
+ if ((tx_len > MTK_NOR_REG_PRGDATA_MAX + 1) ||
+ (rx_len > MTK_NOR_REG_SHIFT_MAX + 1) ||
+ (prg_len > MTK_NOR_PRG_CNT_MAX / 8))
+ return -EINVAL;
+
+ // fill tx data
+ for (i = op->cmd.nbytes; i > 0; i--, reg_offset--) {
+ reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
+ bufbyte = (op->cmd.opcode >> ((i - 1) * BITS_PER_BYTE)) & 0xff;
+ writeb(bufbyte, reg);
+ }
+
+ for (i = op->addr.nbytes; i > 0; i--, reg_offset--) {
+ reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
+ bufbyte = (op->addr.val >> ((i - 1) * BITS_PER_BYTE)) & 0xff;
+ writeb(bufbyte, reg);
+ }
+
+ if (op->data.dir == SPI_MEM_DATA_OUT) {
+ for (i = 0; i < op->dummy.nbytes; i++, reg_offset--) {
+ reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
+ writeb(0, reg);
+ }
+
+ for (i = 0; i < op->data.nbytes; i++, reg_offset--) {
+ reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
+ writeb(((const u8 *)(op->data.buf.out))[i], reg);
+ }
+ }
+
+ for (; reg_offset >= 0; reg_offset--) {
+ reg = sp->base + MTK_NOR_REG_PRGDATA(reg_offset);
+ writeb(0, reg);
+ }
+
+ // trigger op
+ writel(prg_len * BITS_PER_BYTE, sp->base + MTK_NOR_REG_PRG_CNT);
+ ret = mtk_nor_cmd_exec(sp, MTK_NOR_CMD_PROGRAM,
+ prg_len * BITS_PER_BYTE);
+ if (ret)
+ return ret;
+
+ // fetch read data
+ reg_offset = 0;
+ if (op->data.dir == SPI_MEM_DATA_IN) {
+ for (i = op->data.nbytes - 1; i >= 0; i--, reg_offset++) {
+ reg = sp->base + MTK_NOR_REG_SHIFT(reg_offset);
+ ((u8 *)(op->data.buf.in))[i] = readb(reg);
+ }
+ }
+
+ return 0;
+}
+
static int mtk_nor_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
{
struct mtk_nor *sp = spi_controller_get_devdata(mem->spi->master);
@@ -411,7 +489,7 @@ static int mtk_nor_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)

if ((op->data.nbytes == 0) ||
((op->addr.nbytes != 3) && (op->addr.nbytes != 4)))
- return -ENOTSUPP;
+ return mtk_nor_spi_mem_prg(sp, op);

if (op->data.dir == SPI_MEM_DATA_OUT) {
mtk_nor_set_addr(sp, op);
@@ -441,7 +519,7 @@ static int mtk_nor_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
}
}

- return -ENOTSUPP;
+ return mtk_nor_spi_mem_prg(sp, op);
}

static int mtk_nor_setup(struct spi_device *spi)
--
2.26.2
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