[PATCH v4 08/20] mtd: spi-nor-core: Rework hwcaps selection

Pratyush Yadav p.yadav at ti.com
Fri May 22 14:44:57 CEST 2020


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().

Based on the Linux commit c76f5089796a (mtd: spi-nor: Rework hwcaps
selection for the spi-mem case, 2019-08-06)

Signed-off-by: Pratyush Yadav <p.yadav at ti.com>
---
 drivers/mtd/spi/spi-nor-core.c | 168 +++++++++++++++++++++++++--------
 include/linux/mtd/spi-nor.h    |  14 +++
 2 files changed, 144 insertions(+), 38 deletions(-)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index fd99d88501..9db5bffa0a 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -2289,6 +2289,124 @@ static int spi_nor_hwcaps_pp2cmd(u32 hwcaps)
 				  ARRAY_SIZE(hwcaps_pp2cmd));
 }
 
+/**
+ * spi_nor_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_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->spi, op)) {
+		if (nor->mtd.size > SZ_16M)
+			return -ENOTSUPP;
+
+		/* If flash size <= 16MB, 3 address bytes are sufficient */
+		op->addr.nbytes = 3;
+		if (!spi_mem_supports_op(nor->spi, op))
+			return -ENOTSUPP;
+	}
+
+	return 0;
+}
+
+/**
+ * spi_nor_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_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_check_op(nor, &op);
+}
+
+/**
+ * spi_nor_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_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_check_op(nor, &op);
+}
+
+/**
+ * spi_nor_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_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;
+
+	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_check_readop(nor, &params->reads[rdidx]))
+			*hwcaps &= ~BIT(cap);
+
+		ppidx = spi_nor_hwcaps_pp2cmd(BIT(cap));
+		if (ppidx < 0)
+			continue;
+
+		if (spi_nor_check_pp(nor, &params->page_programs[ppidx]))
+			*hwcaps &= ~BIT(cap);
+	}
+}
+
 static int spi_nor_select_read(struct spi_nor *nor,
 			       const struct spi_nor_flash_parameter *params,
 			       u32 shared_hwcaps)
@@ -2372,7 +2490,7 @@ static int spi_nor_default_setup(struct spi_nor *nor,
 				 const struct spi_nor_flash_parameter *params,
 				 const struct spi_nor_hwcaps *hwcaps)
 {
-	u32 ignored_mask, shared_mask;
+	u32 shared_mask;
 	bool enable_quad_io;
 	int err;
 
@@ -2382,17 +2500,12 @@ static int spi_nor_default_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;
-	}
+	/*
+	 * 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_adjust_hwcaps(nor, params, &shared_mask);
 
 	/* Select the (Fast) Read command. */
 	err = spi_nor_select_read(nor, params, shared_mask);
@@ -2487,12 +2600,12 @@ int spi_nor_scan(struct spi_nor *nor)
 	struct spi_nor_flash_parameter params;
 	const struct flash_info *info = NULL;
 	struct mtd_info *mtd = &nor->mtd;
-	struct spi_nor_hwcaps hwcaps = {
-		.mask = SNOR_HWCAPS_READ |
-			SNOR_HWCAPS_READ_FAST |
-			SNOR_HWCAPS_PP,
-	};
 	struct spi_slave *spi = nor->spi;
+	/*
+	 * 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 };
 	int ret;
 
 	/* Reset SPI protocol for all commands. */
@@ -2506,27 +2619,6 @@ int spi_nor_scan(struct spi_nor *nor)
 
 	nor->setup = spi_nor_default_setup;
 
-	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;
-	}
-
 	info = spi_nor_read_id(nor);
 	if (IS_ERR_OR_NULL(info))
 		return -ENOENT;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 922e795ea6..327491fb17 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -312,6 +312,20 @@ 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)
+
 struct spi_nor_read_command {
 	u8			num_mode_clocks;
 	u8			num_wait_states;
-- 
2.26.2



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