From cf4d2ce1eded8de0a678f5e473322eef84adb5e8 Mon Sep 17 00:00:00 2001 From: Alexander Sverdlin Date: Thu, 3 Jul 2025 00:29:26 +0200 Subject: [PATCH] eeprom: at25: fram: Detect and support inside-out chip variants Infineon seems to be confused with the order ID bytes should be presented by the FRAM chips and to be on the safe side they offer chips which are either JEDEC conform or the full opposite of the latter. Examples of the chips which present ID bytes in the reversed order are: CY15B102QN CY15B204QSN Let's support them nevertheless. Except reversing the ID bytes, they also have quite different density encoding even across EXCELON(tm) family. The patch has been tested with the above two chips. Signed-off-by: Alexander Sverdlin Link: https://lore.kernel.org/r/20250702222927.864875-1-alexander.sverdlin@siemens.com Signed-off-by: Greg Kroah-Hartman --- drivers/misc/eeprom/at25.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c index 595ceb9a7126..8a7a53f590f9 100644 --- a/drivers/misc/eeprom/at25.c +++ b/drivers/misc/eeprom/at25.c @@ -388,17 +388,33 @@ static int at25_fram_to_chip(struct device *dev, struct spi_eeprom *chip) /* Get ID of chip */ fm25_aux_read(at25, id, FM25_RDID, FM25_ID_LEN); + /* There are inside-out FRAM variations, detect them and reverse the ID bytes */ + if (id[6] == 0x7f && id[2] == 0xc2) + for (i = 0; i < ARRAY_SIZE(id) / 2; i++) { + u8 tmp = id[i]; + int j = ARRAY_SIZE(id) - i - 1; + + id[i] = id[j]; + id[j] = tmp; + } if (id[6] != 0xc2) { dev_err(dev, "Error: no Cypress FRAM (id %02x)\n", id[6]); return -ENODEV; } - /* Set size found in ID */ - if (id[7] < 0x21 || id[7] > 0x26) { + + switch (id[7]) { + case 0x21 ... 0x26: + chip->byte_len = BIT(id[7] - 0x21 + 4) * 1024; + break; + case 0x2a ... 0x30: + /* CY15B116QN ... CY15B116QN */ + chip->byte_len = BIT(((id[7] >> 1) & 0xf) + 13); + break; + default: dev_err(dev, "Error: unsupported size (id %02x)\n", id[7]); return -ENODEV; } - chip->byte_len = BIT(id[7] - 0x21 + 4) * 1024; if (chip->byte_len > 64 * 1024) chip->flags |= EE_ADDR3; else -- 2.47.2