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Message-Id: <20240521-mcp251xfd-gpio-feature-v3-5-7f829fefefc2@ew.tq-group.com>
Date: Tue, 21 May 2024 15:04:55 +0200
From: Gregor Herburger <gregor.herburger@...tq-group.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
Thomas Kopp <thomas.kopp@...rochip.com>,
Vincent Mailhol <mailhol.vincent@...adoo.fr>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>
Cc: linux-can@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
linux@...tq-group.com, gregor.herburger@...tq-group.com
Subject: [PATCH v3 5/8] can: mcp251xfd: add workaround for errata 5
According to 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 every write to the second byte
causes the overwrite of LAT0/LAT1.
Never write byte 2 of IOCON register to avoid clearing of LAT0/LAT1.
Signed-off-by: Gregor Herburger <gregor.herburger@...tq-group.com>
---
drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c | 89 ++++++++++++++++++++++--
1 file changed, 83 insertions(+), 6 deletions(-)
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
index 52716cce73ec..8499a303ad77 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-regmap.c
@@ -13,9 +13,9 @@
static const struct regmap_config mcp251xfd_regmap_crc;
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);
@@ -39,6 +39,45 @@ mcp251xfd_regmap_nocrc_gather_write(void *context,
return spi_sync_transfer(spi, xfer, ARRAY_SIZE(xfer));
}
+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(*(u16 *)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 = cpu_to_be16(MCP251XFD_SPI_INSTRUCTION_WRITE | reg);
+ return _mcp251xfd_regmap_nocrc_gather_write(context, ®, 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)
{
@@ -197,9 +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);
@@ -230,6 +269,44 @@ mcp251xfd_regmap_crc_gather_write(void *context,
return spi_sync_transfer(spi, xfer, ARRAY_SIZE(xfer));
}
+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_len, val, len);
+ if (ret)
+ return ret;
+
+ /* Write from 0xe07 on */
+ reg += len + 1;
+ return _mcp251xfd_regmap_crc_gather_write(context, ®, 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)
--
2.34.1
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