linux-kernel - [PATCH 5.18 025/112] can: mcp251xfd: mcp251xfd_register_get_dev

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Date:   Mon, 11 Jul 2022 11:06:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Rasmus Villemoes <rasmus.villemoes@...vas.dk>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH 5.18 025/112] can: mcp251xfd: mcp251xfd_register_get_dev_id(): fix endianness conversion

From: Marc Kleine-Budde <mkl@...gutronix.de>

commit 1c0e78a287e3493e22bde8553d02f3b89177eaf7 upstream.

In mcp251xfd_register_get_dev_id() the device ID register is read with
handcrafted SPI transfers. As all registers, this register is in
little endian. Further it is not naturally aligned in struct
mcp251xfd_map_buf_nocrc::data. However after the transfer the register
content is converted from big endian to CPU endianness not taking care
of being unaligned.

Fix the conversion by converting from little endian to CPU endianness
taking the unaligned source into account.

Side note: So far the register content is 0x0 on all mcp251xfd
compatible chips, and is only used for an informative printk.

Link: https://lore.kernel.org/all/20220627092859.809042-1-mkl@pengutronix.de
Fixes: 55e5b97f003e ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Reviewed-by: Rasmus Villemoes <rasmus.villemoes@...vas.dk>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -12,6 +12,7 @@
 // Copyright (c) 2019 Martin Sperl <kernel@...tin.sperl.org>
 //
 
+#include <asm/unaligned.h>
 #include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/device.h>
@@ -1778,7 +1779,7 @@ mcp251xfd_register_get_dev_id(const stru
 	if (err)
 		goto out_kfree_buf_tx;
 
-	*dev_id = be32_to_cpup((__be32 *)buf_rx->data);
+	*dev_id = get_unaligned_le32(buf_rx->data);
 	*effective_speed_hz_slow = xfer[0].effective_speed_hz;
 	*effective_speed_hz_fast = xfer[1].effective_speed_hz;