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spi: mtk_snor: avoid alloc in mtk_snor_cmd_program()

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Rework mtk_snor_cmd_program() to avoid allocating a temporary buffer
for tx data. This improves performance a bit by avoiding the need to
allocate memory and copy data an extra time.

Signed-off-by: Noah.Shen <noah.shen@mediatek.com>
Reviewed-by: Julien Stephan <jstephan@baylibre.com>
Link: https://patch.msgid.link/20260406-mtk-spi-nor-improvements-v1-2-66f675cbbd3e@baylibre.com
Signed-off-by: David Lechner <dlechner@baylibre.com>
This commit is contained in:
Noah.Shen 2026-04-06 15:13:28 -05:00 committed by David Lechner
parent 4f9842e479
commit 4eac47d4eb
1 changed files with 45 additions and 32 deletions
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77
drivers/spi/mtk_snor.c
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@ -383,50 +383,63 @@ static int mtk_snor_pp_unbuffered(struct mtk_snor_priv *priv,
static int mtk_snor_cmd_program(struct mtk_snor_priv *priv,
const struct spi_mem_op *op)
{
u32 tx_len = 0;
u32 trx_len = 0;
int rx_len = 0;
int reg_offset = MTK_NOR_REG_PRGDATA_MAX;
int tx_len, prg_len;
int i;
void __iomem *reg;
u8 *txbuf;
int tx_cnt = 0;
u8 *rxbuf = op->data.buf.in;
int i = 0;
u8 val;
tx_len = 1 + op->addr.nbytes + op->dummy.nbytes;
trx_len = tx_len + op->data.nbytes;
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->data.nbytes;
tx_len += op->dummy.nbytes + op->data.nbytes;
else if (op->data.dir == SPI_MEM_DATA_IN)
rx_len = op->data.nbytes;
txbuf = kmalloc_array(tx_len, sizeof(u8), GFP_KERNEL);
memset(txbuf, 0x0, tx_len * sizeof(u8));
prg_len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes +
op->data.nbytes;
/* Join all bytes to be transferred */
txbuf[tx_cnt] = op->cmd.opcode;
tx_cnt++;
for (i = op->addr.nbytes; i > 0; i--, tx_cnt++)
txbuf[tx_cnt] = ((u8 *)&op->addr.val)[i - 1];
for (i = op->dummy.nbytes; i > 0; i--, tx_cnt++)
txbuf[tx_cnt] = 0x0;
if (op->data.dir == SPI_MEM_DATA_OUT)
for (i = op->data.nbytes; i > 0; i--, tx_cnt++)
txbuf[tx_cnt] = ((u8 *)op->data.buf.out)[i - 1];
/* fill tx data */
for (i = MTK_NOR_REG_PRGDATA_MAX; i >= 0; i--)
writeb(0, priv->base + MTK_NOR_REG_PRGDATA(i));
for (i = op->cmd.nbytes; i > 0; i--, reg_offset--) {
reg = priv->base + MTK_NOR_REG_PRGDATA(reg_offset);
val = (op->cmd.opcode >> ((i - 1) * BITS_PER_BYTE)) & 0xff;
writeb(val, reg);
}
for (i = 0; i < tx_len; i++, reg_offset--)
writeb(txbuf[i], priv->base + MTK_NOR_REG_PRGDATA(reg_offset));
for (i = op->addr.nbytes; i > 0; i--, reg_offset--) {
reg = priv->base + MTK_NOR_REG_PRGDATA(reg_offset);
val = (op->addr.val >> ((i - 1) * BITS_PER_BYTE)) & 0xff;
writeb(val, reg);
}
kfree(txbuf);
for (i = 0; i < op->dummy.nbytes; i++, reg_offset--) {
reg = priv->base + MTK_NOR_REG_PRGDATA(reg_offset);
writeb(0, reg);
}
writel(trx_len * BITS_PER_BYTE, priv->base + MTK_NOR_REG_PRG_CNT);
mtk_snor_cmd_exec(priv, MTK_NOR_CMD_PROGRAM, trx_len * BITS_PER_BYTE);
reg_offset = op->data.nbytes - 1;
for (i = 0; i < op->data.nbytes; i++, reg_offset--) {
reg = priv->base + MTK_NOR_REG_PRGDATA(reg_offset);
writeb(((const u8 *)(op->data.buf.out))[i], reg);
}
for (; reg_offset >= 0; reg_offset--) {
reg = priv->base + MTK_NOR_REG_PRGDATA(reg_offset);
writeb(0, reg);
}
/* trigger op */
writel(prg_len * BITS_PER_BYTE, priv->base + MTK_NOR_REG_PRG_CNT);
mtk_snor_cmd_exec(priv, MTK_NOR_CMD_PROGRAM, prg_len * BITS_PER_BYTE);
/* fetch read data */
reg_offset = 0;
for (i = op->data.nbytes - 1; i >= 0; i--, reg_offset++) {
reg = priv->base + MTK_NOR_REG_SHIFT(reg_offset);
rxbuf[i] = readb(reg);
((u8 *)(op->data.buf.in))[i] = readb(reg);
}
return 0;