[PATCH V4 2/4] arm64: imx8mp: Read values from M24C32-D write-lockable page on DHCOM i.MX8MP

[Marek Vasut]

On 11/28/24 3:20 PM, Christoph Niedermaier wrote:

[...]

> +++ b/board/dhelectronics/common/dh_common.c
> @@ -7,6 +7,7 @@
>   #include <dm.h>
>   #include <i2c_eeprom.h>
>   #include <net.h>
> +#include <u-boot/crc.h>
>   
>   #include "dh_common.h"
>   
> @@ -30,6 +31,148 @@ int dh_get_mac_is_enabled(const char *alias)
>   	return 0;
>   }
>   
> +int dh_read_eeprom_id_page(u8 *eeprom_buffer, const char *alias)
> +{
> +	struct eeprom_id_page *eip = (struct eeprom_id_page *)eeprom_buffer;
> +	struct udevice *dev;
> +	size_t payload_len;
> +	int eeprom_size;
> +	u16 crc16_calc;
> +	u16 crc16_eip;
> +	u8 crc8_calc;
> +	ofnode node;
> +	int ret;
> +
> +	node = ofnode_path(alias);
> +
> +	ret = uclass_get_device_by_ofnode(UCLASS_I2C_EEPROM, node, &dev);
> +	if (ret)
> +		return ret;
> +
> +	eeprom_size = i2c_eeprom_size(dev);
> +	if (eeprom_size < 0) {
> +		printf("%s: Error getting EEPROM ID page size! ret = %d\n", __func__, ret);
> +		return eeprom_size;
> +	} else if (eeprom_size == 0 || eeprom_size > DH_EEPROM_ID_PAGE_MAX_SIZE) {

The else part is not necessary, use plain:

...
  ...
  return eeprom_size;
}

if (eeprom_size == 0 || eeprom_size > DH_EEPROM_ID_PAGE_MAX_SIZE) {
...

> +		eeprom_size = DH_EEPROM_ID_PAGE_MAX_SIZE;
> +		printf("Get invalid EEPROM ID page size %d bytes! Try to read %d bytes.\n",
> +		       eeprom_size, DH_EEPROM_ID_PAGE_MAX_SIZE);
> +	}
> +
> +	ret = i2c_eeprom_read(dev, 0x0, eeprom_buffer, eeprom_size);
> +	if (ret) {
> +		printf("%s: Error reading EEPROM ID page! ret = %d\n", __func__, ret);
> +		return ret;
> +	}
> +
> +	/* Validate header ID */
> +	if (eip->hdr.id[0] != 'D' || eip->hdr.id[1] != 'H' || eip->hdr.id[2] != 'E') {
> +		printf("%s: Error validating header ID! (got %c%c%c (0x%02x 0x%02x 0x%02x) != expected DHE)\n",
> +		       __func__, isprint(eip->hdr.id[0]) ? eip->hdr.id[0] : '.',
> +		       isprint(eip->hdr.id[1]) ? eip->hdr.id[1] : '.',
> +		       isprint(eip->hdr.id[2]) ? eip->hdr.id[2] : '.',
> +		       eip->hdr.id[0], eip->hdr.id[1], eip->hdr.id[2]);
> +		return -EINVAL;
> +	}
> +
> +	/* Validate header checksum */
> +	crc8_calc = crc8(0xff, eeprom_buffer, offsetof(struct eeprom_id_page, hdr.crc8_hdr));
> +	if (eip->hdr.crc8_hdr != crc8_calc) {
> +		printf("%s: Error validating header checksum! (got 0x%02x != calc 0x%02x)\n",
> +		       __func__, eip->hdr.crc8_hdr, crc8_calc);
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Validate header version
> +	 * The payload is defined by the version specified in the header.
> +	 * Currently only version 0x10 is defined, so take the length of
> +	 * the only defined payload as the payload length.
> +	 */
> +	if (eip->hdr.version == DH_EEPROM_ID_PAGE_V1_0) {

Invert this conditional:

...
if (eip->hdr.version != DH_EEPROM_ID_PAGE_V1_0) {
  printf(...);
  return ...;
}

payload_len = sizeof(eip->pl);
...

> +		payload_len = sizeof(eip->pl);
> +	} else {
> +		printf("%s: Error validating version! (0x%02X is not supported)\n",
> +		       __func__, eip->hdr.version);
> +		return -EINVAL;
> +	}
> +
> +	/* Validate payload checksum */
> +	crc16_eip = (eip->hdr.crc16_pl[1] << 8) | eip->hdr.crc16_pl[0];
> +	crc16_calc = crc16(0xffff, eeprom_buffer + sizeof(eip->hdr), payload_len);
> +	if (crc16_eip != crc16_calc) {
> +		printf("%s: Error validating data checksum! (got 0x%02x != calc 0x%02x)\n",
> +		       __func__, crc16_eip, crc16_calc);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}

[...]