Message-ID: <20250509181737.997167-1-Raju.Rangoju@amd.com>
Date: Fri, 9 May 2025 23:47:37 +0530
From: Raju Rangoju <Raju.Rangoju@....com>
To: <broonie@...nel.org>
CC: <linux-spi@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Raju Rangoju
	<Raju.Rangoju@....com>, Krishnamoorthi M <krishnamoorthi.m@....com>, "Akshata
 MukundShetty" <akshata.mukundshetty@....com>
Subject: [PATCH] spi: spi_amd: Add HIDDMA basic write support

SPI index mode has hardware limitation of transferring only 64 bytes per
transaction due to fixed number of FIFO registers. This constraint leads to
performance issues when reading/writing data to/from NAND/NOR flash
devices, as the controller must issue multiple requests to read/write
64-byte chunks, even if the slave can transfer up to 2 or 4 KB in a single
transaction.

The AMD HID2 SPI controller supports DMA mode, allowing for reading/writing
up to 4 KB of data in a single transaction. The existing spi_amd driver
already supports HID2 DMA read operations.

This patch introduces changes to implement HID2 DMA single mode basic write
support for the HID2 SPI controller.

Co-developed-by: Krishnamoorthi M <krishnamoorthi.m@....com>
Signed-off-by: Krishnamoorthi M <krishnamoorthi.m@....com>
Co-developed-by: Akshata MukundShetty <akshata.mukundshetty@....com>
Signed-off-by: Akshata MukundShetty <akshata.mukundshetty@....com>
Signed-off-by: Raju Rangoju <Raju.Rangoju@....com>
---
 drivers/spi/spi-amd.c | 130 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 107 insertions(+), 23 deletions(-)

diff --git a/drivers/spi/spi-amd.c b/drivers/spi/spi-amd.c
index 17fc0b17e756..8567465d2282 100644
--- a/drivers/spi/spi-amd.c
+++ b/drivers/spi/spi-amd.c
@@ -52,10 +52,13 @@
 #define AMD_SPI_SPD7_MASK	GENMASK(13, AMD_SPI_SPD7_SHIFT)
 
 #define AMD_SPI_HID2_INPUT_RING_BUF0	0X100
+#define AMD_SPI_HID2_OUTPUT_BUF0	0x140
 #define AMD_SPI_HID2_CNTRL		0x150
 #define AMD_SPI_HID2_INT_STATUS		0x154
 #define AMD_SPI_HID2_CMD_START		0x156
 #define AMD_SPI_HID2_INT_MASK		0x158
+#define AMD_SPI_HID2_WRITE_CNTRL0	0x160
+#define AMD_SPI_HID2_WRITE_CNTRL1	0x164
 #define AMD_SPI_HID2_READ_CNTRL0	0x170
 #define AMD_SPI_HID2_READ_CNTRL1	0x174
 #define AMD_SPI_HID2_READ_CNTRL2	0x180
@@ -93,6 +96,10 @@ enum amd_spi_versions {
 	AMD_HID2_SPI,
 };
 
+/* SPINAND write command opcodes */
+#define AMD_SPI_OP_PP			0x02	/* Page program */
+#define AMD_SPI_OP_PP_RANDOM		0x84	/* Page program */
+
 enum amd_spi_speed {
 	F_66_66MHz,
 	F_33_33MHz,
@@ -445,6 +452,17 @@ static inline bool amd_is_spi_read_cmd(const u16 op)
 	}
 }
 
+static inline bool amd_is_spi_write_cmd(const u16 op)
+{
+	switch (op) {
+	case AMD_SPI_OP_PP:
+	case AMD_SPI_OP_PP_RANDOM:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static bool amd_spi_supports_op(struct spi_mem *mem,
 				const struct spi_mem_op *op)
 {
@@ -455,7 +473,7 @@ static bool amd_spi_supports_op(struct spi_mem *mem,
 		return false;
 
 	/* AMD SPI controllers support quad mode only for read operations */
-	if (amd_is_spi_read_cmd(op->cmd.opcode)) {
+	if (amd_is_spi_read_cmd(op->cmd.opcode) || amd_is_spi_write_cmd(op->cmd.opcode)) {
 		if (op->data.buswidth > 4)
 			return false;
 
@@ -464,7 +482,8 @@ static bool amd_spi_supports_op(struct spi_mem *mem,
 		 * doesn't support 4-byte address commands.
 		 */
 		if (amd_spi->version == AMD_HID2_SPI) {
-			if (amd_is_spi_read_cmd_4b(op->cmd.opcode) ||
+			if ((amd_is_spi_read_cmd_4b(op->cmd.opcode) ||
+			     amd_is_spi_write_cmd(op->cmd.opcode)) &&
 			    op->data.nbytes > AMD_SPI_HID2_DMA_SIZE)
 				return false;
 		} else if (op->data.nbytes > AMD_SPI_MAX_DATA) {
@@ -490,7 +509,8 @@ static int amd_spi_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
 	 * controller index mode supports maximum of 64 bytes in a single
 	 * transaction.
 	 */
-	if (amd_spi->version == AMD_HID2_SPI && amd_is_spi_read_cmd(op->cmd.opcode))
+	if (amd_spi->version == AMD_HID2_SPI && (amd_is_spi_read_cmd(op->cmd.opcode) ||
+						 amd_is_spi_write_cmd(op->cmd.opcode)))
 		op->data.nbytes = clamp_val(op->data.nbytes, 0, AMD_SPI_HID2_DMA_SIZE);
 	else
 		op->data.nbytes = clamp_val(op->data.nbytes, 0, AMD_SPI_MAX_DATA);
@@ -514,32 +534,91 @@ static void amd_spi_set_addr(struct amd_spi *amd_spi,
 	}
 }
 
+static void amd_spi_hiddma_write(struct amd_spi *amd_spi, const struct spi_mem_op *op)
+{
+	u16 hid_cmd_start, val;
+	u32 hid_regval;
+
+	/*
+	 * Program the HID2 output Buffer0. 4k aligned buf_memory_addr[31:12],
+	 * buf_size[2:0].
+	 */
+	hid_regval = amd_spi->phy_dma_buf | BIT(0);
+	amd_spi_writereg32(amd_spi, AMD_SPI_HID2_OUTPUT_BUF0, hid_regval);
+
+	/* Program max write length in hid2_write_control1 register */
+	hid_regval = amd_spi_readreg32(amd_spi, AMD_SPI_HID2_WRITE_CNTRL1);
+	hid_regval = (hid_regval & ~GENMASK(15, 0)) | ((op->data.nbytes) + 3);
+	amd_spi_writereg32(amd_spi, AMD_SPI_HID2_WRITE_CNTRL1, hid_regval);
+
+	/* Set cmd start bit in hid2_cmd_start register to trigger HID basic write operation */
+	hid_cmd_start = amd_spi_readreg16(amd_spi, AMD_SPI_HID2_CMD_START);
+	amd_spi_writereg16(amd_spi, AMD_SPI_HID2_CMD_START, (hid_cmd_start | BIT(2)));
+
+	/* Check interrupt status of HIDDMA basic write operation in hid2_int_status register */
+	readw_poll_timeout(amd_spi->io_remap_addr + AMD_SPI_HID2_INT_STATUS, val,
+			   (val & BIT(2)), AMD_SPI_IO_SLEEP_US, AMD_SPI_IO_TIMEOUT_US);
+
+	/* Clear the interrupts by writing to hid2_int_status register */
+	val = amd_spi_readreg16(amd_spi, AMD_SPI_HID2_INT_STATUS);
+	amd_spi_writereg16(amd_spi, AMD_SPI_HID2_INT_STATUS, val);
+}
+
 static void amd_spi_mem_data_out(struct amd_spi *amd_spi,
 				 const struct spi_mem_op *op)
 {
 	int base_addr = AMD_SPI_FIFO_BASE + op->addr.nbytes;
 	u64 *buf_64 = (u64 *)op->data.buf.out;
+	u64 addr_val = op->addr.val;
 	u32 nbytes = op->data.nbytes;
 	u32 left_data = nbytes;
 	u8 *buf;
 	int i;
 
-	amd_spi_set_opcode(amd_spi, op->cmd.opcode);
-	amd_spi_set_addr(amd_spi, op);
+	/*
+	 * Condition for using HID write mode. Only for writing complete page data, use HID write.
+	 * Use index mode otherwise.
+	 */
+	if (amd_spi->version == AMD_HID2_SPI && amd_is_spi_write_cmd(op->cmd.opcode)) {
+		void *hid_base_addr = amd_spi->dma_virt_addr + op->addr.nbytes + op->cmd.nbytes;
 
-	for (i = 0; left_data >= 8; i++, left_data -= 8)
-		amd_spi_writereg64(amd_spi, base_addr + op->dummy.nbytes + (i * 8), *buf_64++);
+		/* Write opcode and address in system memory */
+		writeb(op->cmd.opcode, amd_spi->dma_virt_addr);
 
-	buf = (u8 *)buf_64;
-	for (i = 0; i < left_data; i++) {
-		amd_spi_writereg8(amd_spi, base_addr + op->dummy.nbytes + nbytes + i - left_data,
-				  buf[i]);
-	}
+		for (i = 0; i < op->addr.nbytes; i++) {
+			writeb(addr_val & GENMASK(7, 0), hid_base_addr - i - op->cmd.nbytes);
+			addr_val >>= 8;
+		}
 
-	amd_spi_set_tx_count(amd_spi, op->addr.nbytes + op->data.nbytes);
-	amd_spi_set_rx_count(amd_spi, 0);
-	amd_spi_clear_fifo_ptr(amd_spi);
-	amd_spi_execute_opcode(amd_spi);
+		for (i = 0; left_data >= 8; i++, left_data -= 8)
+			writeq(*buf_64++, hid_base_addr + (i * 8));
+
+		buf = (u8 *)buf_64;
+
+		for (i = 0; i < left_data; i++)
+			writeb(buf[i], hid_base_addr + (nbytes - left_data + i));
+
+		amd_spi_hiddma_write(amd_spi, op);
+	} else {
+		amd_spi_set_opcode(amd_spi, op->cmd.opcode);
+		amd_spi_set_addr(amd_spi, op);
+
+		for (i = 0; left_data >= 8; i++, left_data -= 8)
+			amd_spi_writereg64(amd_spi, base_addr + op->dummy.nbytes + (i * 8),
+					   *buf_64++);
+
+		buf = (u8 *)buf_64;
+		for (i = 0; i < left_data; i++) {
+			amd_spi_writereg8(amd_spi,
+					  base_addr + op->dummy.nbytes + nbytes + i - left_data,
+					  buf[i]);
+		}
+
+		amd_spi_set_tx_count(amd_spi, op->addr.nbytes + op->data.nbytes);
+		amd_spi_set_rx_count(amd_spi, 0);
+		amd_spi_clear_fifo_ptr(amd_spi);
+		amd_spi_execute_opcode(amd_spi);
+	}
 }
 
 static void amd_spi_hiddma_read(struct amd_spi *amd_spi, const struct spi_mem_op *op)
@@ -728,23 +807,28 @@ static int amd_spi_setup_hiddma(struct amd_spi *amd_spi, struct device *dev)
 {
 	u32 hid_regval;
 
-	/* Allocate DMA buffer to use for HID basic read operation */
-	amd_spi->dma_virt_addr = dma_alloc_coherent(dev, AMD_SPI_HID2_DMA_SIZE,
-						    &amd_spi->phy_dma_buf, GFP_KERNEL);
+	/* Allocate DMA buffer to use for HID basic read and write operations. For write
+	 * operations, the DMA buffer should include the opcode, address bytes and dummy
+	 * bytes(if any) in addition to the data bytes. Additionally, the hardware requires
+	 * that the buffer address be 4K aligned. So, allocate DMA buffer of size
+	 * 2 * AMD_SPI_HID2_DMA_SIZE.
+	 */
+	amd_spi->dma_virt_addr = dmam_alloc_coherent(dev, AMD_SPI_HID2_DMA_SIZE * 2,
+						     &amd_spi->phy_dma_buf, GFP_KERNEL);
 	if (!amd_spi->dma_virt_addr)
 		return -ENOMEM;
 
 	/*
 	 * Enable interrupts and set mask bits in hid2_int_mask register to generate interrupt
-	 * properly for HIDDMA basic read operations.
+	 * properly for HIDDMA basic read and write operations.
 	 */
 	hid_regval = amd_spi_readreg32(amd_spi, AMD_SPI_HID2_INT_MASK);
-	hid_regval = (hid_regval & GENMASK(31, 8)) | BIT(19);
+	hid_regval = (hid_regval & GENMASK(31, 8)) | BIT(18) | BIT(19);
 	amd_spi_writereg32(amd_spi, AMD_SPI_HID2_INT_MASK, hid_regval);
 
-	/* Configure buffer unit(4k) in hid2_control register */
+	/* Configure buffer unit(4k) and write threshold in hid2_control register */
 	hid_regval = amd_spi_readreg32(amd_spi, AMD_SPI_HID2_CNTRL);
-	amd_spi_writereg32(amd_spi, AMD_SPI_HID2_CNTRL, hid_regval & ~BIT(3));
+	amd_spi_writereg32(amd_spi, AMD_SPI_HID2_CNTRL, (hid_regval | GENMASK(13, 12)) & ~BIT(3));
 
 	return 0;
 }
-- 
2.34.1

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