[PATCH v3 0/4] eeprom: ee1004: Enable devices on multiple busses

[PATCH v3 0/4] eeprom: ee1004: Enable devices on multiple busses

[Eddie James]

The driver previously prevented probing devices on more than one
bus due to locking constraints with the special page addresses. This
constraint can be removed by allocating a reference-counted bus
structure containing the lock, rather than using global variables.
In addition, add devicetree bindings for the EE1004 driver for the
AT30TSE device and add the devices to the Bonnell BMC system.

Changes since v2:
 - Remove of_device.h include
 - Use the full model number of the device for the binding
 - Fix commit name for the bindings documentation and the
   OF matching support

Changes since v1:
 - Add the devicetree changes

Eddie James (4):
  eeprom: ee1004: Enable devices on multiple busses
  dt-bindings: trivial-devices: Add Atmel AT30TSE004A serial eeprom
  eeprom: ee1004: Add OF matching support
  ARM: dts: aspeed: bonnell: Add DIMM SPD

 .../devicetree/bindings/trivial-devices.yaml  |   2 +
 arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts  |  20 ++
 drivers/misc/eeprom/ee1004.c                  | 181 +++++++++++-------
 3 files changed, 134 insertions(+), 69 deletions(-)

-- 
2.31.1

[PATCH v3 1/4] eeprom: ee1004: Enable devices on multiple busses

[Eddie James]

The driver previously prevented probing devices on more than one
bus due to locking constraints with the special page addresses. This
constraint can be removed by allocating a reference-counted bus
structure containing the lock, rather than using global variables.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
Changes since v2:
 - Remove of_device.h include

 drivers/misc/eeprom/ee1004.c | 174 +++++++++++++++++++++--------------
 1 file changed, 105 insertions(+), 69 deletions(-)

diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c
index c8c6deb7ed89..0aed5760e370 100644
--- a/drivers/misc/eeprom/ee1004.c
+++ b/drivers/misc/eeprom/ee1004.c
@@ -9,9 +9,11 @@
  * Copyright (C) 2008 Wolfram Sang, Pengutronix
  */
 
+#include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/list.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
@@ -31,20 +33,24 @@
  * over performance.
  */
 
-#define EE1004_ADDR_SET_PAGE		0x36
+#define EE1004_ADDR_SET_PAGE0		0x36
+#define EE1004_ADDR_SET_PAGE1		0x37
 #define EE1004_NUM_PAGES		2
 #define EE1004_PAGE_SIZE		256
 #define EE1004_PAGE_SHIFT		8
 #define EE1004_EEPROM_SIZE		(EE1004_PAGE_SIZE * EE1004_NUM_PAGES)
 
-/*
- * Mutex protects ee1004_set_page and ee1004_dev_count, and must be held
- * from page selection to end of read.
- */
-static DEFINE_MUTEX(ee1004_bus_lock);
-static struct i2c_client *ee1004_set_page[EE1004_NUM_PAGES];
-static unsigned int ee1004_dev_count;
-static int ee1004_current_page;
+struct ee1004_bus {
+	struct kref kref;
+	struct list_head list;
+	struct mutex lock;
+	struct i2c_adapter *adapter;
+	struct i2c_client *set_page_clients[EE1004_NUM_PAGES];
+	int page;
+};
+
+static LIST_HEAD(ee1004_busses);
+static DEFINE_MUTEX(ee1004_busses_lock);
 
 static const struct i2c_device_id ee1004_ids[] = {
 	{ "ee1004", 0 },
@@ -54,11 +60,11 @@ MODULE_DEVICE_TABLE(i2c, ee1004_ids);
 
 /*-------------------------------------------------------------------------*/
 
-static int ee1004_get_current_page(void)
+static int ee1004_get_current_page(struct ee1004_bus *bus)
 {
 	int err;
 
-	err = i2c_smbus_read_byte(ee1004_set_page[0]);
+	err = i2c_smbus_read_byte(bus->set_page_clients[0]);
 	if (err == -ENXIO) {
 		/* Nack means page 1 is selected */
 		return 1;
@@ -72,33 +78,30 @@ static int ee1004_get_current_page(void)
 	return 0;
 }
 
-static int ee1004_set_current_page(struct device *dev, int page)
+static int ee1004_set_current_page(struct ee1004_bus *bus, int page)
 {
 	int ret;
 
-	if (page == ee1004_current_page)
+	if (page == bus->page)
 		return 0;
 
 	/* Data is ignored */
-	ret = i2c_smbus_write_byte(ee1004_set_page[page], 0x00);
+	ret = i2c_smbus_write_byte(bus->set_page_clients[page], 0x00);
+
 	/*
 	 * Don't give up just yet. Some memory modules will select the page
 	 * but not ack the command. Check which page is selected now.
 	 */
-	if (ret == -ENXIO && ee1004_get_current_page() == page)
+	if (ret == -ENXIO && ee1004_get_current_page(bus) == page)
 		ret = 0;
-	if (ret < 0) {
-		dev_err(dev, "Failed to select page %d (%d)\n", page, ret);
+	if (ret < 0)
 		return ret;
-	}
-
-	dev_dbg(dev, "Selected page %d\n", page);
-	ee1004_current_page = page;
 
+	bus->page = page;
 	return 0;
 }
 
-static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf,
+static ssize_t ee1004_eeprom_read(struct i2c_client *client, struct ee1004_bus *bus, char *buf,
 				  unsigned int offset, size_t count)
 {
 	int status, page;
@@ -106,9 +109,11 @@ static ssize_t ee1004_eeprom_read(struct i2c_client *client, char *buf,
 	page = offset >> EE1004_PAGE_SHIFT;
 	offset &= (1 << EE1004_PAGE_SHIFT) - 1;
 
-	status = ee1004_set_current_page(&client->dev, page);
-	if (status)
+	status = ee1004_set_current_page(bus, page);
+	if (status) {
+		dev_err(&client->dev, "Failed to select page %d (%d)\n", page, status);
 		return status;
+	}
 
 	/* Can't cross page boundaries */
 	if (offset + count > EE1004_PAGE_SIZE)
@@ -125,6 +130,7 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 			   char *buf, loff_t off, size_t count)
 {
 	struct i2c_client *client = kobj_to_i2c_client(kobj);
+	struct ee1004_bus *bus = i2c_get_clientdata(client);
 	size_t requested = count;
 	int ret = 0;
 
@@ -132,10 +138,10 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 	 * Read data from chip, protecting against concurrent access to
 	 * other EE1004 SPD EEPROMs on the same adapter.
 	 */
-	mutex_lock(&ee1004_bus_lock);
+	mutex_lock(&bus->lock);
 
 	while (count) {
-		ret = ee1004_eeprom_read(client, buf, off, count);
+		ret = ee1004_eeprom_read(client, bus, buf, off, count);
 		if (ret < 0)
 			goto out;
 
@@ -144,7 +150,7 @@ static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 		count -= ret;
 	}
 out:
-	mutex_unlock(&ee1004_bus_lock);
+	mutex_unlock(&bus->lock);
 
 	return ret < 0 ? ret : requested;
 }
@@ -158,18 +164,56 @@ static struct bin_attribute *ee1004_attrs[] = {
 
 BIN_ATTRIBUTE_GROUPS(ee1004);
 
-static void ee1004_cleanup(int idx)
+static void ee1004_bus_unregister(struct ee1004_bus *bus)
 {
-	if (--ee1004_dev_count == 0)
-		while (--idx >= 0) {
-			i2c_unregister_device(ee1004_set_page[idx]);
-			ee1004_set_page[idx] = NULL;
-		}
+	i2c_unregister_device(bus->set_page_clients[1]);
+	i2c_unregister_device(bus->set_page_clients[0]);
+}
+
+static void ee1004_bus_release(struct kref *kref)
+{
+	struct ee1004_bus *bus = container_of(kref, struct ee1004_bus, kref);
+
+	ee1004_bus_unregister(bus);
+
+	mutex_lock(&ee1004_busses_lock);
+	list_del(&bus->list);
+	mutex_unlock(&ee1004_busses_lock);
+
+	kfree(bus);
+}
+
+static int ee1004_bus_initialize(struct ee1004_bus *bus, struct i2c_adapter *adapter)
+{
+	bus->set_page_clients[0] = i2c_new_dummy_device(adapter, EE1004_ADDR_SET_PAGE0);
+	if (IS_ERR(bus->set_page_clients[0]))
+		return PTR_ERR(bus->set_page_clients[0]);
+
+	bus->set_page_clients[1] = i2c_new_dummy_device(adapter, EE1004_ADDR_SET_PAGE1);
+	if (IS_ERR(bus->set_page_clients[1])) {
+		i2c_unregister_device(bus->set_page_clients[0]);
+		return PTR_ERR(bus->set_page_clients[1]);
+	}
+
+	bus->page = ee1004_get_current_page(bus);
+	if (bus->page < 0) {
+		ee1004_bus_unregister(bus);
+		return bus->page;
+	}
+
+	kref_init(&bus->kref);
+	list_add(&bus->list, &ee1004_busses);
+	mutex_init(&bus->lock);
+	bus->adapter = adapter;
+
+	return 0;
 }
 
 static int ee1004_probe(struct i2c_client *client)
 {
-	int err, cnr = 0;
+	struct ee1004_bus *bus;
+	bool found = false;
+	int rc = 0;
 
 	/* Make sure we can operate on this adapter */
 	if (!i2c_check_functionality(client->adapter,
@@ -178,53 +222,45 @@ static int ee1004_probe(struct i2c_client *client)
 				     I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_READ_BYTE_DATA))
 		return -EPFNOSUPPORT;
 
-	/* Use 2 dummy devices for page select command */
-	mutex_lock(&ee1004_bus_lock);
-	if (++ee1004_dev_count == 1) {
-		for (cnr = 0; cnr < EE1004_NUM_PAGES; cnr++) {
-			struct i2c_client *cl;
-
-			cl = i2c_new_dummy_device(client->adapter, EE1004_ADDR_SET_PAGE + cnr);
-			if (IS_ERR(cl)) {
-				err = PTR_ERR(cl);
-				goto err_clients;
-			}
-			ee1004_set_page[cnr] = cl;
+	mutex_lock(&ee1004_busses_lock);
+	list_for_each_entry(bus, &ee1004_busses, list) {
+		if (bus->adapter == client->adapter) {
+			kref_get(&bus->kref);
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		bus = kzalloc(sizeof(*bus), GFP_KERNEL);
+		if (!bus) {
+			rc = -ENOMEM;
+			goto unlock;
 		}
 
-		/* Remember current page to avoid unneeded page select */
-		err = ee1004_get_current_page();
-		if (err < 0)
-			goto err_clients;
-		dev_dbg(&client->dev, "Currently selected page: %d\n", err);
-		ee1004_current_page = err;
-	} else if (client->adapter != ee1004_set_page[0]->adapter) {
-		dev_err(&client->dev,
-			"Driver only supports devices on a single I2C bus\n");
-		err = -EOPNOTSUPP;
-		goto err_clients;
+		rc = ee1004_bus_initialize(bus, client->adapter);
+		if (rc) {
+			kfree(bus);
+			goto unlock;
+		}
 	}
-	mutex_unlock(&ee1004_bus_lock);
+
+	i2c_set_clientdata(client, bus);
 
 	dev_info(&client->dev,
 		 "%u byte EE1004-compliant SPD EEPROM, read-only\n",
 		 EE1004_EEPROM_SIZE);
 
-	return 0;
-
- err_clients:
-	ee1004_cleanup(cnr);
-	mutex_unlock(&ee1004_bus_lock);
-
-	return err;
+unlock:
+	mutex_unlock(&ee1004_busses_lock);
+	return rc;
 }
 
 static void ee1004_remove(struct i2c_client *client)
 {
-	/* Remove page select clients if this is the last device */
-	mutex_lock(&ee1004_bus_lock);
-	ee1004_cleanup(EE1004_NUM_PAGES);
-	mutex_unlock(&ee1004_bus_lock);
+	struct ee1004_bus *bus = i2c_get_clientdata(client);
+
+	kref_put(&bus->kref, ee1004_bus_release);
 }
 
 /*-------------------------------------------------------------------------*/
-- 
2.31.1

[PATCH v3 2/4] dt-bindings: trivial-devices: Add Atmel AT30TSE004A serial eeprom

[Eddie James]

The AT30TSE004A EEPROM is compatible with the JEDEC EE1004 standard.
Document it as a trivial I2C device.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
Changes since v2:
 - Use full model name
 - Fix commit name

 Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
index 6f482a254a1d..9ce6308466c5 100644
--- a/Documentation/devicetree/bindings/trivial-devices.yaml
+++ b/Documentation/devicetree/bindings/trivial-devices.yaml
@@ -47,6 +47,8 @@ properties:
           - ams,iaq-core
             # i2c serial eeprom (24cxx)
           - at,24c08
+            # i2c serial eeprom (EE1004 standard)
+          - atmel,at30tse004a
             # i2c trusted platform module (TPM)
           - atmel,at97sc3204t
             # ATSHA204 - i2c h/w symmetric crypto module
-- 
2.31.1

[PATCH v3 3/4] eeprom: ee1004: Add OF matching support

[Eddie James]

Add an OF match table for devicetree instantiation of the
AT30TSE004A EEPROM.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
Changes since v2:
 - Use full model number
 - Fix commit name

 drivers/misc/eeprom/ee1004.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c
index 0aed5760e370..b7566c1d6edd 100644
--- a/drivers/misc/eeprom/ee1004.c
+++ b/drivers/misc/eeprom/ee1004.c
@@ -58,6 +58,12 @@ static const struct i2c_device_id ee1004_ids[] = {
 };
 MODULE_DEVICE_TABLE(i2c, ee1004_ids);
 
+static const struct of_device_id ee1004_of_match[] = {
+	{ .compatible = "atmel,at30tse004a" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ee1004_of_match);
+
 /*-------------------------------------------------------------------------*/
 
 static int ee1004_get_current_page(struct ee1004_bus *bus)
@@ -269,6 +275,7 @@ static struct i2c_driver ee1004_driver = {
 	.driver = {
 		.name = "ee1004",
 		.dev_groups = ee1004_groups,
+		.of_match_table = ee1004_of_match,
 	},
 	.probe_new = ee1004_probe,
 	.remove = ee1004_remove,
-- 
2.31.1

[PATCH v3 4/4] ARM: dts: aspeed: bonnell: Add DIMM SPD

[Eddie James]

Add the DIMM SPD to the processor I2C busses.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
 arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts b/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts
index 79516dc21c01..ab99d915b50e 100644
--- a/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts
+++ b/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts
@@ -232,18 +232,38 @@ cfam0_i2c1: i2c-bus@1 {
 
 			cfam0_i2c10: i2c-bus@a {
 				reg = <10>;	/* OP3A */
+
+				eeprom@50 {
+					compatible = "atmel,at30tse004a";
+					reg = <0x50>;
+				};
 			};
 
 			cfam0_i2c11: i2c-bus@b {
 				reg = <11>;	/* OP3B */
+
+				eeprom@50 {
+					compatible = "atmel,at30tse004a";
+					reg = <0x50>;
+				};
 			};
 
 			cfam0_i2c12: i2c-bus@c {
 				reg = <12>;	/* OP4A */
+
+				eeprom@50 {
+					compatible = "atmel,at30tse004a";
+					reg = <0x50>;
+				};
 			};
 
 			cfam0_i2c13: i2c-bus@d {
 				reg = <13>;	/* OP4B */
+
+				eeprom@50 {
+					compatible = "atmel,at30tse004a";
+					reg = <0x50>;
+				};
 			};
 
 			cfam0_i2c14: i2c-bus@e {
-- 
2.31.1

Re: [PATCH v3 2/4] dt-bindings: trivial-devices: Add Atmel AT30TSE004A serial eeprom

[Krzysztof Kozlowski]

On 22/03/2023 15:03, Eddie James wrote:
> The AT30TSE004A EEPROM is compatible with the JEDEC EE1004 standard.
> Document it as a trivial I2C device.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---


Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v3 4/4] ARM: dts: aspeed: bonnell: Add DIMM SPD

[Joel Stanley]

On Wed, 22 Mar 2023 at 14:04, Eddie James <eajames@linux.ibm.com> wrote:
>
> Add the DIMM SPD to the processor I2C busses.
>
> Signed-off-by: Eddie James <eajames@linux.ibm.com>

Reviewed-by: Joel Stanley <joel@jms.id.au>

I will take this through the aspeed tree.

> ---
>  arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts b/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts
> index 79516dc21c01..ab99d915b50e 100644
> --- a/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts
> +++ b/arch/arm/boot/dts/aspeed-bmc-ibm-bonnell.dts
> @@ -232,18 +232,38 @@ cfam0_i2c1: i2c-bus@1 {
>
>                         cfam0_i2c10: i2c-bus@a {
>                                 reg = <10>;     /* OP3A */
> +
> +                               eeprom@50 {
> +                                       compatible = "atmel,at30tse004a";
> +                                       reg = <0x50>;
> +                               };
>                         };
>
>                         cfam0_i2c11: i2c-bus@b {
>                                 reg = <11>;     /* OP3B */
> +
> +                               eeprom@50 {
> +                                       compatible = "atmel,at30tse004a";
> +                                       reg = <0x50>;
> +                               };
>                         };
>
>                         cfam0_i2c12: i2c-bus@c {
>                                 reg = <12>;     /* OP4A */
> +
> +                               eeprom@50 {
> +                                       compatible = "atmel,at30tse004a";
> +                                       reg = <0x50>;
> +                               };
>                         };
>
>                         cfam0_i2c13: i2c-bus@d {
>                                 reg = <13>;     /* OP4B */
> +
> +                               eeprom@50 {
> +                                       compatible = "atmel,at30tse004a";
> +                                       reg = <0x50>;
> +                               };
>                         };
>
>                         cfam0_i2c14: i2c-bus@e {
> --
> 2.31.1
>

Re: [PATCH v3 1/4] eeprom: ee1004: Enable devices on multiple busses

[Greg KH]

On Wed, Mar 22, 2023 at 09:03:45AM -0500, Eddie James wrote:
> The driver previously prevented probing devices on more than one
> bus due to locking constraints with the special page addresses. This
> constraint can be removed by allocating a reference-counted bus
> structure containing the lock, rather than using global variables.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
> Changes since v2:
>  - Remove of_device.h include
> 
>  drivers/misc/eeprom/ee1004.c | 174 +++++++++++++++++++++--------------
>  1 file changed, 105 insertions(+), 69 deletions(-)
> 
> diff --git a/drivers/misc/eeprom/ee1004.c b/drivers/misc/eeprom/ee1004.c
> index c8c6deb7ed89..0aed5760e370 100644
> --- a/drivers/misc/eeprom/ee1004.c
> +++ b/drivers/misc/eeprom/ee1004.c
> @@ -9,9 +9,11 @@
>   * Copyright (C) 2008 Wolfram Sang, Pengutronix
>   */
>  
> +#include <linux/err.h>
>  #include <linux/i2c.h>
>  #include <linux/init.h>
>  #include <linux/kernel.h>
> +#include <linux/list.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/module.h>
>  #include <linux/mutex.h>
> @@ -31,20 +33,24 @@
>   * over performance.
>   */
>  
> -#define EE1004_ADDR_SET_PAGE		0x36
> +#define EE1004_ADDR_SET_PAGE0		0x36
> +#define EE1004_ADDR_SET_PAGE1		0x37
>  #define EE1004_NUM_PAGES		2
>  #define EE1004_PAGE_SIZE		256
>  #define EE1004_PAGE_SHIFT		8
>  #define EE1004_EEPROM_SIZE		(EE1004_PAGE_SIZE * EE1004_NUM_PAGES)
>  
> -/*
> - * Mutex protects ee1004_set_page and ee1004_dev_count, and must be held
> - * from page selection to end of read.
> - */
> -static DEFINE_MUTEX(ee1004_bus_lock);
> -static struct i2c_client *ee1004_set_page[EE1004_NUM_PAGES];
> -static unsigned int ee1004_dev_count;
> -static int ee1004_current_page;
> +struct ee1004_bus {
> +	struct kref kref;
> +	struct list_head list;
> +	struct mutex lock;
> +	struct i2c_adapter *adapter;
> +	struct i2c_client *set_page_clients[EE1004_NUM_PAGES];
> +	int page;
> +};
> +
> +static LIST_HEAD(ee1004_busses);
> +static DEFINE_MUTEX(ee1004_busses_lock);

This really looks like you are just emulating a tiny portion of the
driver core (busses, lists of busses, reference counting, etc.)

Why not just use an aux device instead and get all of that logic "for
free" in a way that will be properly shown to userspace?  Right now it
has no idea what is happening here with individual portions of the
device and the like.

Please look into that instead of this hand-rolled device model.

thanks,

greg k-h