[PATCH v4 3/3] mtd: spi-nor: Rework hwcaps selection for the spi-mem case

From: Vignesh Raghavendra
Date: Thu Aug 01 2019 - 12:22:24 EST

From: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>

The spi-mem layer provides a spi_mem_supports_op() function to check
whether a specific operation is supported by the controller or not.
This is much more accurate than the hwcaps selection logic based on
SPI_{RX,TX}_ flags.

Rework the hwcaps selection logic to use spi_mem_supports_op() when
nor->spimem != NULL.

Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx>
---
drivers/mtd/spi-nor/spi-nor.c | 183 +++++++++++++++++++++++++++-------
include/linux/mtd/spi-nor.h | 14 +++
2 files changed, 161 insertions(+), 36 deletions(-)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 866962c715b4..02b40f08ac36 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2952,6 +2952,129 @@ static int spi_nor_read_sfdp(struct spi_nor *nor, u32 addr,
return ret;
}

+/**
+ * spi_nor_spimem_check_op - check if the operation is supported
+ * by controller
+ *@nor: pointer to a 'struct spi_nor'
+ *@op: pointer to op template to be checked
+ *
+ * Returns 0 if operation is supported, -ENOTSUPP otherwise.
+ */
+static int spi_nor_spimem_check_op(struct spi_nor *nor,
+ struct spi_mem_op *op)
+{
+ /*
+ * First test with 4 address bytes. The opcode itself might
+ * be a 3B addressing opcode but we don't care, because
+ * SPI controller implementation should not check the opcode,
+ * but just the sequence.
+ */
+ op->addr.nbytes = 4;
+ if (!spi_mem_supports_op(nor->spimem, op)) {
+ /* If flash size <16MB, 3 address bytes are sufficient */
+ if (nor->mtd.size <= SZ_16M) {
+ op->addr.nbytes = 3;
+ if (!spi_mem_supports_op(nor->spimem, op))
+ return -ENOTSUPP;
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * spi_nor_spimem_check_readop - check if the read op is supported
+ * by controller
+ *@nor: pointer to a 'struct spi_nor'
+ *@read: pointer to op template to be checked
+ *
+ * Returns 0 if operation is supported, -ENOTSUPP otherwise.
+ */
+static int spi_nor_spimem_check_readop(struct spi_nor *nor,
+ const struct spi_nor_read_command *read)
+{
+ struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(read->opcode, 1),
+ SPI_MEM_OP_ADDR(3, 0, 1),
+ SPI_MEM_OP_DUMMY(0, 1),
+ SPI_MEM_OP_DATA_IN(0, NULL, 1));
+
+ op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(read->proto);
+ op.addr.buswidth = spi_nor_get_protocol_addr_nbits(read->proto);
+ op.data.buswidth = spi_nor_get_protocol_data_nbits(read->proto);
+ op.dummy.buswidth = op.addr.buswidth;
+ op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
+ op.dummy.buswidth / 8;
+
+ return spi_nor_spimem_check_op(nor, &op);
+}
+
+/**
+ * spi_nor_spimem_check_pp - check if the page program op is supported
+ * by controller
+ *@nor: pointer to a 'struct spi_nor'
+ *@pp: pointer to op template to be checked
+ *
+ * Returns 0 if operation is supported, -ENOTSUPP otherwise.
+ */
+static int spi_nor_spimem_check_pp(struct spi_nor *nor,
+ const struct spi_nor_pp_command *pp)
+{
+ struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(pp->opcode, 1),
+ SPI_MEM_OP_ADDR(3, 0, 1),
+ SPI_MEM_OP_NO_DUMMY,
+ SPI_MEM_OP_DATA_OUT(0, NULL, 1));
+
+ op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(pp->proto);
+ op.addr.buswidth = spi_nor_get_protocol_addr_nbits(pp->proto);
+ op.data.buswidth = spi_nor_get_protocol_data_nbits(pp->proto);
+
+ return spi_nor_spimem_check_op(nor, &op);
+}
+
+/**
+ * spi_nor_spimem_adjust_hwcaps - Find optimal Read/Write protocol
+ * based on SPI controller capabilities
+ * @nor: pointer to a 'struct spi_nor'
+ * @params: pointer to the 'struct spi_nor_flash_parameter'
+ * representing SPI NOR flash capabilities
+ * @hwcaps: pointer to resulting capabilities after adjusting
+ * according to controller and flash's capability
+ */
+static void
+spi_nor_spimem_adjust_hwcaps(struct spi_nor *nor,
+ const struct spi_nor_flash_parameter *params,
+ u32 *hwcaps)
+{
+ unsigned int cap;
+
+ /* DTR modes are not supported yet, mask them all. */
+ *hwcaps &= ~SNOR_HWCAPS_DTR;
+
+ /* X-X-X modes are not supported yet, mask them all. */
+ *hwcaps &= ~SNOR_HWCAPS_X_X_X;
+
+ /* Start with read commands. */
+ for (cap = 0; cap < sizeof(*hwcaps) * BITS_PER_BYTE; cap++) {
+ int rdidx, ppidx;
+
+ if (!(*hwcaps & BIT(cap)))
+ continue;
+
+ rdidx = spi_nor_hwcaps_read2cmd(BIT(cap));
+ if (rdidx >= 0 &&
+ spi_nor_spimem_check_readop(nor, &params->reads[rdidx]))
+ *hwcaps &= ~BIT(cap);
+
+ ppidx = spi_nor_hwcaps_pp2cmd(BIT(cap));
+ if (ppidx < 0)
+ continue;
+
+ if (spi_nor_spimem_check_pp(nor,
+ &params->page_programs[ppidx]))
+ *hwcaps &= ~BIT(cap);
+ }
+}
+
/**
* spi_nor_read_sfdp_dma_unsafe() - read Serial Flash Discoverable Parameters.
* @nor: pointer to a 'struct spi_nor'
@@ -4361,16 +4484,25 @@ static int spi_nor_setup(struct spi_nor *nor,
*/
shared_mask = hwcaps->mask & params->hwcaps.mask;

- /* SPI n-n-n protocols are not supported yet. */
- ignored_mask = (SNOR_HWCAPS_READ_2_2_2 |
- SNOR_HWCAPS_READ_4_4_4 |
- SNOR_HWCAPS_READ_8_8_8 |
- SNOR_HWCAPS_PP_4_4_4 |
- SNOR_HWCAPS_PP_8_8_8);
- if (shared_mask & ignored_mask) {
- dev_dbg(nor->dev,
- "SPI n-n-n protocols are not supported yet.\n");
- shared_mask &= ~ignored_mask;
+ if (nor->spimem) {
+ /*
+ * When called from spi_nor_probe(), all caps are set and we
+ * need to discard some of them based on what the SPI
+ * controller actually supports (using spi_mem_supports_op()).
+ */
+ spi_nor_spimem_adjust_hwcaps(nor, params, &shared_mask);
+ } else {
+ /*
+ * SPI n-n-n protocols are not supported when the SPI
+ * controller directly implements the spi_nor interface.
+ * Yet another reason to switch to spi-mem.
+ */
+ ignored_mask = SNOR_HWCAPS_X_X_X;
+ if (shared_mask & ignored_mask) {
+ dev_dbg(nor->dev,
+ "SPI n-n-n protocols are not supported.\n");
+ shared_mask &= ~ignored_mask;
+ }
}

/* Select the (Fast) Read command. */
@@ -4713,11 +4845,11 @@ static int spi_nor_probe(struct spi_mem *spimem)
struct spi_device *spi = spimem->spi;
struct flash_platform_data *data = dev_get_platdata(&spi->dev);
struct spi_nor *nor;
- struct spi_nor_hwcaps hwcaps = {
- .mask = SNOR_HWCAPS_READ |
- SNOR_HWCAPS_READ_FAST |
- SNOR_HWCAPS_PP,
- };
+ /*
+ * Enable all caps by default. The core will mask them after
+ * checking what's really supported using spi_mem_supports_op().
+ */
+ const struct spi_nor_hwcaps hwcaps = { .mask = SNOR_HWCAPS_ALL };
char *flash_name;
int ret;

@@ -4731,27 +4863,6 @@ static int spi_nor_probe(struct spi_mem *spimem)

spi_mem_set_drvdata(spimem, nor);

- if (spi->mode & SPI_RX_OCTAL) {
- hwcaps.mask |= SNOR_HWCAPS_READ_1_1_8;
-
- if (spi->mode & SPI_TX_OCTAL)
- hwcaps.mask |= (SNOR_HWCAPS_READ_1_8_8 |
- SNOR_HWCAPS_PP_1_1_8 |
- SNOR_HWCAPS_PP_1_8_8);
- } else if (spi->mode & SPI_RX_QUAD) {
- hwcaps.mask |= SNOR_HWCAPS_READ_1_1_4;
-
- if (spi->mode & SPI_TX_QUAD)
- hwcaps.mask |= (SNOR_HWCAPS_READ_1_4_4 |
- SNOR_HWCAPS_PP_1_1_4 |
- SNOR_HWCAPS_PP_1_4_4);
- } else if (spi->mode & SPI_RX_DUAL) {
- hwcaps.mask |= SNOR_HWCAPS_READ_1_1_2;
-
- if (spi->mode & SPI_TX_DUAL)
- hwcaps.mask |= SNOR_HWCAPS_READ_1_2_2;
- }
-
if (data && data->name)
nor->mtd.name = data->name;

diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 4f35b1877889..5f1acb1867dd 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -524,6 +524,20 @@ struct spi_nor_hwcaps {
#define SNOR_HWCAPS_PP_1_8_8 BIT(21)
#define SNOR_HWCAPS_PP_8_8_8 BIT(22)

+#define SNOR_HWCAPS_X_X_X (SNOR_HWCAPS_READ_2_2_2 | \
+ SNOR_HWCAPS_READ_4_4_4 | \
+ SNOR_HWCAPS_READ_8_8_8 | \
+ SNOR_HWCAPS_PP_4_4_4 | \
+ SNOR_HWCAPS_PP_8_8_8)
+
+#define SNOR_HWCAPS_DTR (SNOR_HWCAPS_READ_1_1_1_DTR | \
+ SNOR_HWCAPS_READ_1_2_2_DTR | \
+ SNOR_HWCAPS_READ_1_4_4_DTR | \
+ SNOR_HWCAPS_READ_1_8_8_DTR)
+
+#define SNOR_HWCAPS_ALL (SNOR_HWCAPS_READ_MASK | \
+ SNOR_HWCAPS_PP_MASK)
+
/**
* spi_nor_scan() - scan the SPI NOR
* @nor: the spi_nor structure
--
2.22.0