1 files changed, 126 insertions, 39 deletions

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
index 297491516a26..70d5ff0ae7ac 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
@@ -2,28 +2,20 @@
 //
 // mcp251xfd - Microchip MCP251xFD Family CAN controller driver
 //
-// Copyright (c) 2019, 2020 Pengutronix,
-//                          Marc Kleine-Budde <kernel@pengutronix.de>
+// Copyright (c) 2019, 2020, 2021 Pengutronix,
+//               Marc Kleine-Budde <kernel@pengutronix.de>
 //
 
 #include "mcp251xfd.h"
 
-#include <asm/unaligned.h>
+#include <linux/unaligned.h>
 
 static const struct regmap_config mcp251xfd_regmap_crc;
 
 static int
-mcp251xfd_regmap_nocrc_write(void *context, const void *data, size_t count)
-{
-	struct spi_device *spi = context;
-
-	return spi_write(spi, data, count);
-}
-
-static int
-mcp251xfd_regmap_nocrc_gather_write(void *context,
-				    const void *reg, size_t reg_len,
-				    const void *val, size_t val_len)
+_mcp251xfd_regmap_nocrc_gather_write(void *context,
+				     const void *reg, size_t reg_len,
+				     const void *val, size_t val_len)
 {
 	struct spi_device *spi = context;
 	struct mcp251xfd_priv *priv = spi_get_drvdata(spi);
@@ -47,22 +39,81 @@ mcp251xfd_regmap_nocrc_gather_write(void *context,
 	return spi_sync_transfer(spi, xfer, ARRAY_SIZE(xfer));
 }
 
-static inline bool mcp251xfd_update_bits_read_reg(unsigned int reg)
+static int
+mcp251xfd_regmap_nocrc_gather_write(void *context,
+				    const void *reg_p, size_t reg_len,
+				    const void *val, size_t val_len)
+{
+	const u16 byte_exclude = MCP251XFD_REG_IOCON +
+				 mcp251xfd_first_byte_set(MCP251XFD_REG_IOCON_GPIO_MASK);
+	u16 reg = be16_to_cpu(*(__be16 *)reg_p) & MCP251XFD_SPI_ADDRESS_MASK;
+	int ret;
+
+	/* Never write to bits 16..23 of IOCON register to avoid clearing of LAT0/LAT1
+	 *
+	 * According to MCP2518FD Errata DS80000789E 5 writing IOCON register using one
+	 * SPI write command clears LAT0/LAT1.
+	 *
+	 * Errata Fix/Work Around suggests to write registers with single byte
+	 * write instructions. However, it seems that the byte at 0xe06(IOCON[23:16])
+	 * is for read-only access and writing to it causes the clearing of LAT0/LAT1.
+	 */
+	if (reg <= byte_exclude && reg + val_len > byte_exclude) {
+		size_t len = byte_exclude - reg;
+
+		/* Write up to 0xe05 */
+		ret = _mcp251xfd_regmap_nocrc_gather_write(context, reg_p, reg_len, val, len);
+		if (ret)
+			return ret;
+
+		/* Write from 0xe07 on */
+		reg += len + 1;
+		reg = (__force unsigned short)cpu_to_be16(MCP251XFD_SPI_INSTRUCTION_WRITE | reg);
+		return _mcp251xfd_regmap_nocrc_gather_write(context, &reg, reg_len,
+							    val + len + 1,
+							    val_len - len - 1);
+	}
+
+	return _mcp251xfd_regmap_nocrc_gather_write(context, reg_p, reg_len,
+						  val, val_len);
+}
+
+static int
+mcp251xfd_regmap_nocrc_write(void *context, const void *data, size_t count)
+{
+	const size_t data_offset = sizeof(__be16);
+
+	return mcp251xfd_regmap_nocrc_gather_write(context, data, data_offset,
+						   data + data_offset, count - data_offset);
+}
+
+static inline bool
+mcp251xfd_update_bits_read_reg(const struct mcp251xfd_priv *priv,
+			       unsigned int reg)
 {
+	struct mcp251xfd_rx_ring *ring;
+	int n;
+
 	switch (reg) {
 	case MCP251XFD_REG_INT:
 	case MCP251XFD_REG_TEFCON:
-	case MCP251XFD_REG_FIFOCON(MCP251XFD_RX_FIFO(0)):
 	case MCP251XFD_REG_FLTCON(0):
 	case MCP251XFD_REG_ECCSTAT:
 	case MCP251XFD_REG_CRC:
 		return false;
 	case MCP251XFD_REG_CON:
-	case MCP251XFD_REG_FIFOSTA(MCP251XFD_RX_FIFO(0)):
 	case MCP251XFD_REG_OSC:
 	case MCP251XFD_REG_ECCCON:
+	case MCP251XFD_REG_IOCON:
 		return true;
 	default:
+		mcp251xfd_for_each_rx_ring(priv, ring, n) {
+			if (reg == MCP251XFD_REG_FIFOCON(ring->fifo_nr))
+				return false;
+			if (reg == MCP251XFD_REG_FIFOSTA(ring->fifo_nr))
+				return true;
+		}
+
 		WARN(1, "Status of reg 0x%04x unknown.\n", reg);
 	}
 
@@ -92,7 +143,7 @@ mcp251xfd_regmap_nocrc_update_bits(void *context, unsigned int reg,
 	last_byte = mcp251xfd_last_byte_set(mask);
 	len = last_byte - first_byte + 1;
 
-	if (mcp251xfd_update_bits_read_reg(reg)) {
+	if (mcp251xfd_update_bits_read_reg(priv, reg)) {
 		struct spi_transfer xfer[2] = { };
 		struct spi_message msg;
 
@@ -129,10 +180,9 @@ mcp251xfd_regmap_nocrc_update_bits(void *context, unsigned int reg,
 	tmp_le32 = orig_le32 & ~mask_le32;
 	tmp_le32 |= val_le32 & mask_le32;
 
-	mcp251xfd_spi_cmd_write_nocrc(&buf_tx->cmd, reg + first_byte);
-	memcpy(buf_tx->data, &tmp_le32, len);
-
-	return spi_write(spi, buf_tx, sizeof(buf_tx->cmd) + len);
+	reg += first_byte;
+	mcp251xfd_spi_cmd_write_nocrc(&buf_tx->cmd, reg);
+	return mcp251xfd_regmap_nocrc_gather_write(context, &buf_tx->cmd, 2, &tmp_le32, len);
 }
 
 static int
@@ -186,9 +236,9 @@ mcp251xfd_regmap_nocrc_read(void *context,
 }
 
 static int
-mcp251xfd_regmap_crc_gather_write(void *context,
-				  const void *reg_p, size_t reg_len,
-				  const void *val, size_t val_len)
+_mcp251xfd_regmap_crc_gather_write(void *context,
+				   const void *reg_p, size_t reg_len,
+				   const void *val, size_t val_len)
 {
 	struct spi_device *spi = context;
 	struct mcp251xfd_priv *priv = spi_get_drvdata(spi);
@@ -220,6 +270,44 @@ mcp251xfd_regmap_crc_gather_write(void *context,
 }
 
 static int
+mcp251xfd_regmap_crc_gather_write(void *context,
+				  const void *reg_p, size_t reg_len,
+				  const void *val, size_t val_len)
+{
+	const u16 byte_exclude = MCP251XFD_REG_IOCON +
+				 mcp251xfd_first_byte_set(MCP251XFD_REG_IOCON_GPIO_MASK);
+	u16 reg = *(u16 *)reg_p;
+	int ret;
+
+	/* Never write to bits 16..23 of IOCON register to avoid clearing of LAT0/LAT1
+	 *
+	 * According to MCP2518FD Errata DS80000789E 5 writing IOCON register using one
+	 * SPI write command clears LAT0/LAT1.
+	 *
+	 * Errata Fix/Work Around suggests to write registers with single byte
+	 * write instructions. However, it seems that the byte at 0xe06(IOCON[23:16])
+	 * is for read-only access and writing to it causes the clearing of LAT0/LAT1.
+	 */
+	if (reg <= byte_exclude  && reg + val_len > byte_exclude) {
+		size_t len = byte_exclude - reg;
+
+		/* Write up to 0xe05 */
+		ret = _mcp251xfd_regmap_crc_gather_write(context, &reg, reg_len, val, len);
+		if (ret)
+			return ret;
+
+		/* Write from 0xe07 on */
+		reg += len + 1;
+		return _mcp251xfd_regmap_crc_gather_write(context, &reg, reg_len,
+							  val + len + 1,
+							  val_len - len - 1);
+	}
+
+	return _mcp251xfd_regmap_crc_gather_write(context, reg_p, reg_len,
+						  val, val_len);
+}
+
+static int
 mcp251xfd_regmap_crc_write(void *context,
 			   const void *data, size_t count)
 {
@@ -250,7 +338,6 @@ mcp251xfd_regmap_crc_read_check_crc(const struct mcp251xfd_map_buf_crc * const b
 	return 0;
 }
 
-
 static int
 mcp251xfd_regmap_crc_read_one(struct mcp251xfd_priv *priv,
 			      struct spi_message *msg, unsigned int data_len)
@@ -325,19 +412,21 @@ mcp251xfd_regmap_crc_read(void *context,
 		 * register. It increments once per SYS clock tick,
 		 * which is 20 or 40 MHz.
 		 *
-		 * Observation shows that if the lowest byte (which is
-		 * transferred first on the SPI bus) of that register
-		 * is 0x00 or 0x80 the calculated CRC doesn't always
-		 * match the transferred one.
+		 * Observation on the mcp2518fd shows that if the
+		 * lowest byte (which is transferred first on the SPI
+		 * bus) of that register is 0x00 or 0x80 the
+		 * calculated CRC doesn't always match the transferred
+		 * one. On the mcp2517fd this problem is not limited
+		 * to the first byte being 0x00 or 0x80.
 		 *
 		 * If the highest bit in the lowest byte is flipped
 		 * the transferred CRC matches the calculated one. We
-		 * assume for now the CRC calculation in the chip
-		 * works on wrong data and the transferred data is
-		 * correct.
+		 * assume for now the CRC operates on the correct
+		 * data.
 		 */
 		if (reg == MCP251XFD_REG_TBC &&
-		    (buf_rx->data[0] == 0x0 || buf_rx->data[0] == 0x80)) {
+		    ((buf_rx->data[0] & 0xf8) == 0x0 ||
+		     (buf_rx->data[0] & 0xf8) == 0x80)) {
 			/* Flip highest bit in lowest byte of le32 */
 			buf_rx->data[0] ^= 0x80;
 
@@ -347,10 +436,8 @@ mcp251xfd_regmap_crc_read(void *context,
 								  val_len);
 			if (!err) {
 				/* If CRC is now correct, assume
-				 * transferred data was OK, flip bit
-				 * back to original value.
+				 * flipped data is OK.
 				 */
-				buf_rx->data[0] ^= 0x80;
 				goto out;
 			}
 		}
@@ -369,7 +456,7 @@ mcp251xfd_regmap_crc_read(void *context,
 		 * to the caller. It will take care of both cases.
 		 *
 		 */
-		if (reg == MCP251XFD_REG_OSC) {
+		if (reg == MCP251XFD_REG_OSC && val_len == sizeof(__le32)) {
 			err = 0;
 			goto out;
 		}
@@ -388,7 +475,7 @@ mcp251xfd_regmap_crc_read(void *context,
 
 		return err;
 	}
- out:
+out:
 	memcpy(val_buf, buf_rx->data, val_len);
 
 	return 0;