[PATCH v9 0/5] add support for FRAM

[PATCH v9 0/5] add support for FRAM

[Jiri Prchal]

Adds support for Cypress FRAMs.

Jiri Prchal (5):
  nvmem: prepare basics for FRAM support
  nvmem: eeprom: at25: add support for FRAM
  dt-bindings: nvmem: at25: add for FRAM support
  nvmem: eeprom: at25: export FRAM serial num
  nvmem: eeprom: add documentation of sysfs fram and sernum file

 .../ABI/testing/sysfs-class-spi-eeprom        |  20 +++
 .../devicetree/bindings/eeprom/at25.yaml      |  31 +++-
 drivers/misc/eeprom/Kconfig                   |   5 +-
 drivers/misc/eeprom/at25.c                    | 161 ++++++++++++++----
 drivers/nvmem/core.c                          |   4 +
 include/linux/nvmem-provider.h                |   1 +
 6 files changed, 184 insertions(+), 38 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-spi-eeprom

-- 
2.25.1

[PATCH v9 1/5] nvmem: prepare basics for FRAM support

[Jiri Prchal]

Added enum and string for FRAM to expose it as "fram".

Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
---
v2: no change here
v3: resend and added more recipients
v4: resend
v5: no change here
v6: changed commit subject
v7: no change here
v8: changed subject
v9: no change here
---
 drivers/nvmem/core.c           | 4 ++++
 include/linux/nvmem-provider.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 177f5bf27c6d..01ef9a934b0a 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -180,6 +180,7 @@ static const char * const nvmem_type_str[] = {
 	[NVMEM_TYPE_EEPROM] = "EEPROM",
 	[NVMEM_TYPE_OTP] = "OTP",
 	[NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
+	[NVMEM_TYPE_FRAM] = "FRAM",
 };
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -359,6 +360,9 @@ static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
 	if (!config->base_dev)
 		return -EINVAL;
 
+	if (config->type == NVMEM_TYPE_FRAM)
+		bin_attr_nvmem_eeprom_compat.attr.name = "fram";
+
 	nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
 	nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
 	nvmem->eeprom.size = nvmem->size;
diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index e162b757b6d5..890003565761 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -25,6 +25,7 @@ enum nvmem_type {
 	NVMEM_TYPE_EEPROM,
 	NVMEM_TYPE_OTP,
 	NVMEM_TYPE_BATTERY_BACKED,
+	NVMEM_TYPE_FRAM,
 };
 
 #define NVMEM_DEVID_NONE	(-1)
-- 
2.25.1

[PATCH v9 2/5] nvmem: eeprom: at25: add support for FRAM

[Jiri Prchal]

Added support for Cypress FRAMs.
These frams have ID and some of them have serial number too.
Size of them is recognized by ID. They don't have pages, it could
be read or written at once, but it's limited in this driver to
io limit 4096.

Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
---
v2: fixed warning at %zd at int
Reported-by: kernel test robot <lkp@intel.com>
v3: resend and added more recipients
v4: resend
v5: used in-kernel function int_pow
v6: no change here
v7: moved definition of sernum size to patch 4
v8: changed buffer type to u8
v9: removed needless has_sernum
---
 drivers/misc/eeprom/Kconfig |   5 +-
 drivers/misc/eeprom/at25.c  | 134 ++++++++++++++++++++++++++++--------
 2 files changed, 107 insertions(+), 32 deletions(-)

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index 0f791bfdc1f5..f0a7531f354c 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -32,12 +32,13 @@ config EEPROM_AT24
 	  will be called at24.
 
 config EEPROM_AT25
-	tristate "SPI EEPROMs from most vendors"
+	tristate "SPI EEPROMs (FRAMs) from most vendors"
 	depends on SPI && SYSFS
 	select NVMEM
 	select NVMEM_SYSFS
 	help
-	  Enable this driver to get read/write support to most SPI EEPROMs,
+	  Enable this driver to get read/write support to most SPI EEPROMs
+	  and Cypress FRAMs,
 	  after you configure the board init code to know about each eeprom
 	  on your target board.
 
diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index b76e4901b4a4..e59b6852816d 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models
+ *	     and Cypress FRAMs FM25 models
  *
  * Copyright (C) 2006 David Brownell
  */
@@ -16,6 +17,9 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/eeprom.h>
 #include <linux/property.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/math.h>
 
 /*
  * NOTE: this is an *EEPROM* driver.  The vagaries of product naming
@@ -42,6 +46,9 @@ struct at25_data {
 #define	AT25_WRSR	0x01		/* write status register */
 #define	AT25_READ	0x03		/* read byte(s) */
 #define	AT25_WRITE	0x02		/* write byte(s)/sector */
+#define	FM25_SLEEP	0xb9		/* enter sleep mode */
+#define	FM25_RDID	0x9f		/* read device ID */
+#define	FM25_RDSN	0xc3		/* read S/N */
 
 #define	AT25_SR_nRDY	0x01		/* nRDY = write-in-progress */
 #define	AT25_SR_WEN	0x02		/* write enable (latched) */
@@ -51,6 +58,8 @@ struct at25_data {
 
 #define	AT25_INSTR_BIT3	0x08		/* Additional address bit in instr */
 
+#define	FM25_ID_LEN	9		/* ID length */
+
 #define EE_MAXADDRLEN	3		/* 24 bit addresses, up to 2 MBytes */
 
 /* Specs often allow 5 msec for a page write, sometimes 20 msec;
@@ -58,6 +67,9 @@ struct at25_data {
  */
 #define	EE_TIMEOUT	25
 
+#define	IS_EEPROM	0
+#define	IS_FRAM		1
+
 /*-------------------------------------------------------------------------*/
 
 #define	io_limit	PAGE_SIZE	/* bytes */
@@ -129,6 +141,36 @@ static int at25_ee_read(void *priv, unsigned int offset,
 	return status;
 }
 
+/*
+ * read extra registers as ID or serial number
+ */
+static int fm25_aux_read(struct at25_data *at25, u8 *buf, uint8_t command,
+			 int len)
+{
+	int status;
+	struct spi_transfer t[2];
+	struct spi_message m;
+
+	spi_message_init(&m);
+	memset(t, 0, sizeof(t));
+
+	t[0].tx_buf = &command;
+	t[0].len = 1;
+	spi_message_add_tail(&t[0], &m);
+
+	t[1].rx_buf = buf;
+	t[1].len = len;
+	spi_message_add_tail(&t[1], &m);
+
+	mutex_lock(&at25->lock);
+
+	status = spi_sync(at25->spi, &m);
+	dev_dbg(&at25->spi->dev, "read %d aux bytes --> %d\n", len, status);
+
+	mutex_unlock(&at25->lock);
+	return status;
+}
+
 static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at25_data *at25 = priv;
@@ -303,34 +345,37 @@ static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
 	return 0;
 }
 
+static const struct of_device_id at25_of_match[] = {
+	{ .compatible = "atmel,at25", .data = (const void *)IS_EEPROM },
+	{ .compatible = "cypress,fm25", .data = (const void *)IS_FRAM },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, at25_of_match);
+
 static int at25_probe(struct spi_device *spi)
 {
 	struct at25_data	*at25 = NULL;
 	struct spi_eeprom	chip;
 	int			err;
 	int			sr;
-	int			addrlen;
+	u8 id[FM25_ID_LEN];
+	const struct of_device_id *match;
+	int is_fram = 0;
+
+	match = of_match_device(of_match_ptr(at25_of_match), &spi->dev);
+	if (match)
+		is_fram = (int)(uintptr_t)match->data;
 
 	/* Chip description */
 	if (!spi->dev.platform_data) {
-		err = at25_fw_to_chip(&spi->dev, &chip);
-		if (err)
-			return err;
+		if (!is_fram) {
+			err = at25_fw_to_chip(&spi->dev, &chip);
+			if (err)
+				return err;
+		}
 	} else
 		chip = *(struct spi_eeprom *)spi->dev.platform_data;
 
-	/* For now we only support 8/16/24 bit addressing */
-	if (chip.flags & EE_ADDR1)
-		addrlen = 1;
-	else if (chip.flags & EE_ADDR2)
-		addrlen = 2;
-	else if (chip.flags & EE_ADDR3)
-		addrlen = 3;
-	else {
-		dev_dbg(&spi->dev, "unsupported address type\n");
-		return -EINVAL;
-	}
-
 	/* Ping the chip ... the status register is pretty portable,
 	 * unlike probing manufacturer IDs.  We do expect that system
 	 * firmware didn't write it in the past few milliseconds!
@@ -349,9 +394,44 @@ static int at25_probe(struct spi_device *spi)
 	at25->chip = chip;
 	at25->spi = spi;
 	spi_set_drvdata(spi, at25);
-	at25->addrlen = addrlen;
 
-	at25->nvmem_config.type = NVMEM_TYPE_EEPROM;
+	if (is_fram) {
+		/* Get ID of chip */
+		fm25_aux_read(at25, id, FM25_RDID, FM25_ID_LEN);
+		if (id[6] != 0xc2) {
+			dev_err(&spi->dev,
+				"Error: no Cypress FRAM (id %02x)\n", id[6]);
+			return -ENODEV;
+		}
+		/* set size found in ID */
+		if (id[7] < 0x21 || id[7] > 0x26) {
+			dev_err(&spi->dev, "Error: unsupported size (id %02x)\n", id[7]);
+			return -ENODEV;
+		}
+		chip.byte_len = int_pow(2, id[7] - 0x21 + 4) * 1024;
+
+		if (at25->chip.byte_len > 64 * 1024)
+			at25->chip.flags |= EE_ADDR3;
+		else
+			at25->chip.flags |= EE_ADDR2;
+
+		at25->chip.page_size = PAGE_SIZE;
+		strncpy(at25->chip.name, "fm25", sizeof(at25->chip.name));
+	}
+
+	/* For now we only support 8/16/24 bit addressing */
+	if (at25->chip.flags & EE_ADDR1)
+		at25->addrlen = 1;
+	else if (at25->chip.flags & EE_ADDR2)
+		at25->addrlen = 2;
+	else if (at25->chip.flags & EE_ADDR3)
+		at25->addrlen = 3;
+	else {
+		dev_dbg(&spi->dev, "unsupported address type\n");
+		return -EINVAL;
+	}
+
+	at25->nvmem_config.type = is_fram ? NVMEM_TYPE_FRAM : NVMEM_TYPE_EEPROM;
 	at25->nvmem_config.name = dev_name(&spi->dev);
 	at25->nvmem_config.dev = &spi->dev;
 	at25->nvmem_config.read_only = chip.flags & EE_READONLY;
@@ -370,23 +450,17 @@ static int at25_probe(struct spi_device *spi)
 	if (IS_ERR(at25->nvmem))
 		return PTR_ERR(at25->nvmem);
 
-	dev_info(&spi->dev, "%d %s %s eeprom%s, pagesize %u\n",
-		(chip.byte_len < 1024) ? chip.byte_len : (chip.byte_len / 1024),
-		(chip.byte_len < 1024) ? "Byte" : "KByte",
-		at25->chip.name,
-		(chip.flags & EE_READONLY) ? " (readonly)" : "",
-		at25->chip.page_size);
+	dev_info(&spi->dev, "%d %s %s %s%s, pagesize %u\n",
+		 (chip.byte_len < 1024) ? chip.byte_len : (chip.byte_len / 1024),
+		 (chip.byte_len < 1024) ? "Byte" : "KByte",
+		 at25->chip.name, is_fram ? "fram" : "eeprom",
+		 (chip.flags & EE_READONLY) ? " (readonly)" : "",
+		 at25->chip.page_size);
 	return 0;
 }
 
 /*-------------------------------------------------------------------------*/
 
-static const struct of_device_id at25_of_match[] = {
-	{ .compatible = "atmel,at25", },
-	{ }
-};
-MODULE_DEVICE_TABLE(of, at25_of_match);
-
 static struct spi_driver at25_driver = {
 	.driver = {
 		.name		= "at25",
-- 
2.25.1

[PATCH v9 3/5] dt-bindings: nvmem: at25: add for FRAM support

[Jiri Prchal]

Added dt binding documentation.

Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
---
v2: fixed dt_binding_check warnings thanks to Rob Herring
v3: resend and added more recipients
v4: resend
v5: no change here
v6: no change here
v7: no change here
v8: changed subject
v9: no change here
---
 .../devicetree/bindings/eeprom/at25.yaml      | 31 +++++++++++++++----
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/eeprom/at25.yaml b/Documentation/devicetree/bindings/eeprom/at25.yaml
index 121a601db22e..840ee7a83a14 100644
--- a/Documentation/devicetree/bindings/eeprom/at25.yaml
+++ b/Documentation/devicetree/bindings/eeprom/at25.yaml
@@ -4,14 +4,16 @@
 $id: "http://devicetree.org/schemas/eeprom/at25.yaml#"
 $schema: "http://devicetree.org/meta-schemas/core.yaml#"
 
-title: SPI EEPROMs compatible with Atmel's AT25
+title: SPI EEPROMs or FRAMs compatible with Atmel's AT25
 
 maintainers:
   - Christian Eggers <ceggers@arri.de>
 
 properties:
   $nodename:
-    pattern: "^eeprom@[0-9a-f]{1,2}$"
+    anyOf:
+      - pattern: "^eeprom@[0-9a-f]{1,2}$"
+      - pattern: "^fram@[0-9a-f]{1,2}$"
 
   # There are multiple known vendors who manufacture EEPROM chips compatible
   # with Atmel's AT25. The compatible string requires two items where the
@@ -31,6 +33,7 @@ properties:
               - microchip,25lc040
               - st,m95m02
               - st,m95256
+              - cypress,fm25
 
           - const: atmel,at25
 
@@ -48,7 +51,7 @@ properties:
     $ref: /schemas/types.yaml#/definitions/uint32
     enum: [1, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072]
     description:
-      Size of the eeprom page.
+      Size of the eeprom page. FRAMs don't have pages.
 
   size:
     $ref: /schemas/types.yaml#/definitions/uint32
@@ -101,9 +104,19 @@ required:
   - compatible
   - reg
   - spi-max-frequency
-  - pagesize
-  - size
-  - address-width
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          not:
+            contains:
+              const: cypress,fm25
+    then:
+      required:
+        - pagesize
+        - size
+        - address-width
 
 additionalProperties: false
 
@@ -126,4 +139,10 @@ examples:
             size = <32768>;
             address-width = <16>;
         };
+
+        fram@1 {
+            compatible = "cypress,fm25", "atmel,at25";
+            reg = <1>;
+            spi-max-frequency = <40000000>;
+        };
     };
-- 
2.25.1

[PATCH v9 4/5] nvmem: eeprom: at25: export FRAM serial num

[Jiri Prchal]

This exports serial number of FRAM in sysfs file named "sernum".
Formatted in hex, each byte separated by space.
Example:
$ cat /sys/class/spi_master/spi0/spi0.0/sernum
ef cd ab 89 67 45 23 01

Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
---
v2: no change here
v3: resend and added more recipients
v4: resend
v5: reworked up on Greg comments: no spaces in string, sysfs done correctly
v6: no change here
v7: moved FM25_SN_LEN, static array, used sysfs_emit, DEVICE_ATTR_RO
v8: clarify sysfs_emit format
v9: sizeof parentheses, export with spaces MSB first
---
 drivers/misc/eeprom/at25.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index e59b6852816d..19280e9f118d 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -31,6 +31,7 @@
  *   AT25M02, AT25128B
  */
 
+#define	FM25_SN_LEN	8		/* serial number length */
 struct at25_data {
 	struct spi_device	*spi;
 	struct mutex		lock;
@@ -38,6 +39,7 @@ struct at25_data {
 	unsigned		addrlen;
 	struct nvmem_config	nvmem_config;
 	struct nvmem_device	*nvmem;
+	u8 sernum[FM25_SN_LEN];
 };
 
 #define	AT25_WREN	0x06		/* latch the write enable */
@@ -171,6 +173,21 @@ static int fm25_aux_read(struct at25_data *at25, u8 *buf, uint8_t command,
 	return status;
 }
 
+static ssize_t sernum_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct at25_data *at25;
+
+	at25 = dev_get_drvdata(dev);
+	return sysfs_emit(buf, "%*ph\n", sizeof(at25->sernum), at25->sernum);
+}
+static DEVICE_ATTR_RO(sernum);
+
+static struct attribute *sernum_attrs[] = {
+	&dev_attr_sernum.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(sernum);
+
 static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at25_data *at25 = priv;
@@ -359,6 +376,8 @@ static int at25_probe(struct spi_device *spi)
 	int			err;
 	int			sr;
 	u8 id[FM25_ID_LEN];
+	u8 sernum[FM25_SN_LEN];
+	int i;
 	const struct of_device_id *match;
 	int is_fram = 0;
 
@@ -415,6 +434,13 @@ static int at25_probe(struct spi_device *spi)
 		else
 			at25->chip.flags |= EE_ADDR2;
 
+		if (id[8]) {
+			fm25_aux_read(at25, sernum, FM25_RDSN, FM25_SN_LEN);
+			/* swap byte order */
+			for (i = 0; i < FM25_SN_LEN; i++)
+				at25->sernum[i] = sernum[FM25_SN_LEN - 1 - i];
+		}
+
 		at25->chip.page_size = PAGE_SIZE;
 		strncpy(at25->chip.name, "fm25", sizeof(at25->chip.name));
 	}
@@ -465,6 +491,7 @@ static struct spi_driver at25_driver = {
 	.driver = {
 		.name		= "at25",
 		.of_match_table = at25_of_match,
+		.dev_groups	= sernum_groups,
 	},
 	.probe		= at25_probe,
 };
-- 
2.25.1

[PATCH v9 5/5] nvmem: eeprom: add documentation of sysfs fram and sernum file

[Jiri Prchal]

Added sysfs fram and sernum file documentation.

Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
---
v5: new
v6: no change here
v7: no change here
v8: added fram file doc
v9: rewritten description
---
 .../ABI/testing/sysfs-class-spi-eeprom        | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-spi-eeprom

diff --git a/Documentation/ABI/testing/sysfs-class-spi-eeprom b/Documentation/ABI/testing/sysfs-class-spi-eeprom
new file mode 100644
index 000000000000..4e69c78f9f65
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-spi-eeprom
@@ -0,0 +1,20 @@
+What:		/sys/class/spi_master/spi<bus>/spi<bus>.<dev>/sernum
+Date:		May 2021
+KernelVersion:	5.14
+Contact:	Jiri Prchal <jiri.prchal@aksignal.cz>
+Description:
+	Contains the serial number of the Cypress FRAM (FM25VN) if it is
+	present.  It will be displayed as a 8 byte hex string, as read
+	from the device.
+
+	This is a read-only attribute.
+
+What:		/sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fram
+Date:		June 2021
+KernelVersion:	5.14
+Contact:	Jiri Prchal <jiri.prchal@aksignal.cz>
+Description:
+	Contains the FRAM binary data. Same as EEPROM, just another file
+	name to indicate that it employs ferroelectric process.
+	It performs write operations at bus speed - no write delays, capable
+	of 10^14 read/write cycles and 151 years data retention.
-- 
2.25.1

Re: [PATCH v9 1/5] nvmem: prepare basics for FRAM support

[Greg Kroah-Hartman]

On Fri, Jun 11, 2021 at 07:26:48AM +0200, Jiri Prchal wrote:
> Added enum and string for FRAM to expose it as "fram".

I have no idea what "FRAM" is, nor what "fram" is.

And why do you not add the documentation update here in this same
commit?  This is where you are adding it, trying to dig later in the
series to notice that you really did provide this is a pain, and is
harder to track.

Please provide more information here in the changelog and move the
Documentation addition here into this patch.

thanks,

greg k-h

Re: [PATCH v9 2/5] nvmem: eeprom: at25: add support for FRAM

[Greg Kroah-Hartman]

On Fri, Jun 11, 2021 at 07:26:49AM +0200, Jiri Prchal wrote:
> Added support for Cypress FRAMs.

Which devices exactly are you adding support for?

> These frams have ID and some of them have serial number too.
> Size of them is recognized by ID. They don't have pages, it could
> be read or written at once, but it's limited in this driver to
> io limit 4096.
> 
> Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
> ---
> v2: fixed warning at %zd at int
> Reported-by: kernel test robot <lkp@intel.com>
> v3: resend and added more recipients
> v4: resend
> v5: used in-kernel function int_pow
> v6: no change here
> v7: moved definition of sernum size to patch 4
> v8: changed buffer type to u8
> v9: removed needless has_sernum
> ---
>  drivers/misc/eeprom/Kconfig |   5 +-
>  drivers/misc/eeprom/at25.c  | 134 ++++++++++++++++++++++++++++--------
>  2 files changed, 107 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
> index 0f791bfdc1f5..f0a7531f354c 100644
> --- a/drivers/misc/eeprom/Kconfig
> +++ b/drivers/misc/eeprom/Kconfig
> @@ -32,12 +32,13 @@ config EEPROM_AT24
>  	  will be called at24.
>  
>  config EEPROM_AT25
> -	tristate "SPI EEPROMs from most vendors"
> +	tristate "SPI EEPROMs (FRAMs) from most vendors"
>  	depends on SPI && SYSFS
>  	select NVMEM
>  	select NVMEM_SYSFS
>  	help
> -	  Enable this driver to get read/write support to most SPI EEPROMs,
> +	  Enable this driver to get read/write support to most SPI EEPROMs
> +	  and Cypress FRAMs,
>  	  after you configure the board init code to know about each eeprom
>  	  on your target board.
>  
> diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
> index b76e4901b4a4..e59b6852816d 100644
> --- a/drivers/misc/eeprom/at25.c
> +++ b/drivers/misc/eeprom/at25.c
> @@ -1,6 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-or-later
>  /*
>   * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models
> + *	     and Cypress FRAMs FM25 models
>   *
>   * Copyright (C) 2006 David Brownell
>   */
> @@ -16,6 +17,9 @@
>  #include <linux/spi/spi.h>
>  #include <linux/spi/eeprom.h>
>  #include <linux/property.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/math.h>
>  
>  /*
>   * NOTE: this is an *EEPROM* driver.  The vagaries of product naming
> @@ -42,6 +46,9 @@ struct at25_data {
>  #define	AT25_WRSR	0x01		/* write status register */
>  #define	AT25_READ	0x03		/* read byte(s) */
>  #define	AT25_WRITE	0x02		/* write byte(s)/sector */
> +#define	FM25_SLEEP	0xb9		/* enter sleep mode */
> +#define	FM25_RDID	0x9f		/* read device ID */
> +#define	FM25_RDSN	0xc3		/* read S/N */
>  
>  #define	AT25_SR_nRDY	0x01		/* nRDY = write-in-progress */
>  #define	AT25_SR_WEN	0x02		/* write enable (latched) */
> @@ -51,6 +58,8 @@ struct at25_data {
>  
>  #define	AT25_INSTR_BIT3	0x08		/* Additional address bit in instr */
>  
> +#define	FM25_ID_LEN	9		/* ID length */
> +
>  #define EE_MAXADDRLEN	3		/* 24 bit addresses, up to 2 MBytes */
>  
>  /* Specs often allow 5 msec for a page write, sometimes 20 msec;
> @@ -58,6 +67,9 @@ struct at25_data {
>   */
>  #define	EE_TIMEOUT	25
>  
> +#define	IS_EEPROM	0
> +#define	IS_FRAM		1
> +
>  /*-------------------------------------------------------------------------*/
>  
>  #define	io_limit	PAGE_SIZE	/* bytes */
> @@ -129,6 +141,36 @@ static int at25_ee_read(void *priv, unsigned int offset,
>  	return status;
>  }
>  
> +/*
> + * read extra registers as ID or serial number
> + */
> +static int fm25_aux_read(struct at25_data *at25, u8 *buf, uint8_t command,
> +			 int len)
> +{
> +	int status;
> +	struct spi_transfer t[2];
> +	struct spi_message m;
> +
> +	spi_message_init(&m);
> +	memset(t, 0, sizeof(t));
> +
> +	t[0].tx_buf = &command;
> +	t[0].len = 1;
> +	spi_message_add_tail(&t[0], &m);
> +
> +	t[1].rx_buf = buf;
> +	t[1].len = len;
> +	spi_message_add_tail(&t[1], &m);
> +
> +	mutex_lock(&at25->lock);
> +
> +	status = spi_sync(at25->spi, &m);
> +	dev_dbg(&at25->spi->dev, "read %d aux bytes --> %d\n", len, status);
> +
> +	mutex_unlock(&at25->lock);
> +	return status;
> +}
> +
>  static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
>  {
>  	struct at25_data *at25 = priv;
> @@ -303,34 +345,37 @@ static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
>  	return 0;
>  }
>  
> +static const struct of_device_id at25_of_match[] = {
> +	{ .compatible = "atmel,at25", .data = (const void *)IS_EEPROM },
> +	{ .compatible = "cypress,fm25", .data = (const void *)IS_FRAM },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, at25_of_match);
> +
>  static int at25_probe(struct spi_device *spi)
>  {
>  	struct at25_data	*at25 = NULL;
>  	struct spi_eeprom	chip;
>  	int			err;
>  	int			sr;
> -	int			addrlen;
> +	u8 id[FM25_ID_LEN];
> +	const struct of_device_id *match;
> +	int is_fram = 0;
> +
> +	match = of_match_device(of_match_ptr(at25_of_match), &spi->dev);
> +	if (match)
> +		is_fram = (int)(uintptr_t)match->data;

Why the double cast?

And "uintptr_t" is not a kernel type.  This originally is just a void *,
so no need to "double cast" it here, right?

thanks,

greg k-h

Re: [PATCH v9 4/5] nvmem: eeprom: at25: export FRAM serial num

[Greg Kroah-Hartman]

On Fri, Jun 11, 2021 at 07:26:51AM +0200, Jiri Prchal wrote:
> This exports serial number of FRAM in sysfs file named "sernum".
> Formatted in hex, each byte separated by space.
> Example:
> $ cat /sys/class/spi_master/spi0/spi0.0/sernum
> ef cd ab 89 67 45 23 01

Again, add the Documentation update to this commit so it can be reviewed
easier.

thanks,

greg k-h

Re: [PATCH v9 5/5] nvmem: eeprom: add documentation of sysfs fram and sernum file

[Greg Kroah-Hartman]

On Fri, Jun 11, 2021 at 07:26:52AM +0200, Jiri Prchal wrote:
> Added sysfs fram and sernum file documentation.
> 
> Signed-off-by: Jiri Prchal <jiri.prchal@aksignal.cz>
> ---
> v5: new
> v6: no change here
> v7: no change here
> v8: added fram file doc
> v9: rewritten description
> ---
>  .../ABI/testing/sysfs-class-spi-eeprom        | 20 +++++++++++++++++++
>  1 file changed, 20 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-spi-eeprom
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-spi-eeprom b/Documentation/ABI/testing/sysfs-class-spi-eeprom
> new file mode 100644
> index 000000000000..4e69c78f9f65
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-spi-eeprom
> @@ -0,0 +1,20 @@
> +What:		/sys/class/spi_master/spi<bus>/spi<bus>.<dev>/sernum
> +Date:		May 2021
> +KernelVersion:	5.14
> +Contact:	Jiri Prchal <jiri.prchal@aksignal.cz>
> +Description:
> +	Contains the serial number of the Cypress FRAM (FM25VN) if it is
> +	present.  It will be displayed as a 8 byte hex string, as read
> +	from the device.
> +
> +	This is a read-only attribute.
> +
> +What:		/sys/class/spi_master/spi<bus>/spi<bus>.<dev>/fram
> +Date:		June 2021
> +KernelVersion:	5.14
> +Contact:	Jiri Prchal <jiri.prchal@aksignal.cz>
> +Description:
> +	Contains the FRAM binary data. Same as EEPROM, just another file
> +	name to indicate that it employs ferroelectric process.
> +	It performs write operations at bus speed - no write delays, capable
> +	of 10^14 read/write cycles and 151 years data retention.

Are you sure of these statistics?  Don't promise something here that
might not be true, this is not a marketing document :)

thanks,

greg k-h

Re: [PATCH v9 1/5] nvmem: prepare basics for FRAM support

[Jiří Prchal]

On 11. 06. 21 10:48, Greg Kroah-Hartman wrote:
> On Fri, Jun 11, 2021 at 07:26:48AM +0200, Jiri Prchal wrote:
>> Added enum and string for FRAM to expose it as "fram".
> 
> I have no idea what "FRAM" is, nor what "fram" is.
> 
> And why do you not add the documentation update here in this same
> commit?  This is where you are adding it, trying to dig later in the
> series to notice that you really did provide this is a pain, and is
> harder to track.
> 
> Please provide more information here in the changelog and move the
> Documentation addition here into this patch.

Should I also join #1 and 2 together?

Re: [PATCH v9 5/5] nvmem: eeprom: add documentation of sysfs fram and sernum file

[Jiří Prchal]

On 11. 06. 21 10:53, Greg Kroah-Hartman wrote:
> On Fri, Jun 11, 2021 at 07:26:52AM +0200, Jiri Prchal wrote:
>> +Description:
>> +	Contains the FRAM binary data. Same as EEPROM, just another file
>> +	name to indicate that it employs ferroelectric process.
>> +	It performs write operations at bus speed - no write delays, capable
>> +	of 10^14 read/write cycles and 151 years data retention.
> 
> Are you sure of these statistics?  Don't promise something here that
> might not be true, this is not a marketing document :)

Just copied from datasheet. Is write at bus speed OK? And about others: 
much more then EEPROM would be OK? Or don't write about it?

Re: [PATCH v9 5/5] nvmem: eeprom: add documentation of sysfs fram and sernum file

[Greg Kroah-Hartman]

On Fri, Jun 11, 2021 at 11:01:57AM +0200, Jiří Prchal wrote:
> 
> 
> On 11. 06. 21 10:53, Greg Kroah-Hartman wrote:
> > On Fri, Jun 11, 2021 at 07:26:52AM +0200, Jiri Prchal wrote:
> > > +Description:
> > > +	Contains the FRAM binary data. Same as EEPROM, just another file
> > > +	name to indicate that it employs ferroelectric process.
> > > +	It performs write operations at bus speed - no write delays, capable
> > > +	of 10^14 read/write cycles and 151 years data retention.
> > 
> > Are you sure of these statistics?  Don't promise something here that
> > might not be true, this is not a marketing document :)
> 
> Just copied from datasheet. Is write at bus speed OK? And about others: much
> more then EEPROM would be OK? Or don't write about it?

I would not even mention it :)

Re: [PATCH v9 1/5] nvmem: prepare basics for FRAM support

[Greg Kroah-Hartman]

On Fri, Jun 11, 2021 at 10:59:07AM +0200, Jiří Prchal wrote:
> 
> 
> On 11. 06. 21 10:48, Greg Kroah-Hartman wrote:
> > On Fri, Jun 11, 2021 at 07:26:48AM +0200, Jiri Prchal wrote:
> > > Added enum and string for FRAM to expose it as "fram".
> > 
> > I have no idea what "FRAM" is, nor what "fram" is.
> > 
> > And why do you not add the documentation update here in this same
> > commit?  This is where you are adding it, trying to dig later in the
> > series to notice that you really did provide this is a pain, and is
> > harder to track.
> > 
> > Please provide more information here in the changelog and move the
> > Documentation addition here into this patch.
> 
> Should I also join #1 and 2 together?

I do not remember what patch 2 is now, sorry.  All you really need is
the documentation update merged in here, I don't recall patch 2 being an
issue.

thanks,

greg k-h

Re: [PATCH v9 1/5] nvmem: prepare basics for FRAM support

[Enrico Weigelt, metux IT consult]

On 11.06.21 10:48, Greg Kroah-Hartman wrote:
> On Fri, Jun 11, 2021 at 07:26:48AM +0200, Jiri Prchal wrote:
>> Added enum and string for FRAM to expose it as "fram".
> 
> I have no idea what "FRAM" is, nor what "fram" is.

perhaps ferroelectric RAM ?

https://en.wikipedia.org/wiki/Ferroelectric_RAM


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