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* [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
@ 2008-01-30 10:36 Bryan Wu
  2008-01-30 11:00 ` Jiri Slaby
  0 siblings, 1 reply; 11+ messages in thread
From: Bryan Wu @ 2008-01-30 10:36 UTC (permalink / raw)
  To: linux-kernel; +Cc: Mike Frysinger, Bryan Wu

From: Mike Frysinger <michael.frysinger@analog.com>

initial char driver for otp memory
(only read supported atm ... needs real examples/docs for write support)

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
---
 drivers/char/Kconfig    |   28 +++++++
 drivers/char/Makefile   |    1 +
 drivers/char/bfin-otp.c |  203 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 232 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/bfin-otp.c

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 4666295..2a426db 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -492,6 +492,34 @@ config BRIQ_PANEL
 
 	  It's safe to say N here.
 
+config BFIN_OTP
+	tristate "Blackfin On-Chip OTP Memory Support"
+	depends on BLACKFIN && (BF52x || BF54x)
+	default y
+	help
+	  If you say Y here, you will get support for a character device
+	  interface into the One Time Programmable memory pages that are
+	  stored on the Blackfin processor.  This will not get you access
+	  to the secure memory pages however.  You will need to write your
+	  own secure code and reader for that.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called bfin-otp.
+
+	  If unsure, it is safe to say Y.
+
+config BFIN_OTP_WRITE_ENABLE
+	bool "Enable writing support of OTP pages"
+	depends on BFIN_OTP
+	default n
+	help
+	  If you say Y here, you will enable support for writing of the
+	  OTP pages.  This is dangerous by nature as you can only program
+	  the pages once, so only enable this option when you actually
+	  need it so as to not inadvertently clobber data.
+
+	  If unsure, say N.
+
 config PRINTER
 	tristate "Parallel printer support"
 	depends on PARPORT
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 96fc01e..b2f1c77 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -60,6 +60,7 @@ obj-$(CONFIG_VIOTAPE)		+= viotape.o
 obj-$(CONFIG_HVCS)		+= hvcs.o
 obj-$(CONFIG_SGI_MBCS)		+= mbcs.o
 obj-$(CONFIG_BRIQ_PANEL)	+= briq_panel.o
+obj-$(CONFIG_BFIN_OTP)		+= bfin-otp.o
 
 obj-$(CONFIG_PRINTER)		+= lp.o
 obj-$(CONFIG_TIPAR)		+= tipar.o
diff --git a/drivers/char/bfin-otp.c b/drivers/char/bfin-otp.c
new file mode 100644
index 0000000..896a987
--- /dev/null
+++ b/drivers/char/bfin-otp.c
@@ -0,0 +1,203 @@
+/*
+ * Blackfin On-Chip OTP Memory Interface
+ *  Supports BF52x/BF54x
+ *
+ * Copyright 2007-2008 Analog Devices Inc.
+ *
+ * Enter bugs at http://blackfin.uclinux.org/
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+
+#include <asm/blackfin.h>
+#include <asm/uaccess.h>
+
+#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
+#define stampit() stamp("here i am")
+
+#define DRIVER_NAME "bfin-otp"
+#define PFX DRIVER_NAME ": "
+
+DEFINE_MUTEX(bfin_otp_lock);
+
+/* OTP Boot ROM functions */
+#define _BOOTROM_OTP_COMMAND           0xEF000018
+#define _BOOTROM_OTP_READ              0xEF00001A
+#define _BOOTROM_OTP_WRITE             0xEF00001C
+
+static u32 (* const otp_command)(u32 command, u32 value) = (void *)_BOOTROM_OTP_COMMAND;
+static u32 (* const otp_read)(u32 page, u32 flags, u64 *page_content) = (void *)_BOOTROM_OTP_READ;
+static u32 (* const otp_write)(u32 page, u32 flags, u64 *page_content) = (void *)_BOOTROM_OTP_WRITE;
+
+/* otp_command(): defines for "command" */
+#define OTP_INIT             0x00000001
+#define OTP_CLOSE            0x00000002
+
+/* otp_{read,write}(): defines for "flags" */
+#define OTP_LOWER_HALF       0x00000000 /* select upper/lower 64-bit half (bit 0) */
+#define OTP_UPPER_HALF       0x00000001
+#define OTP_NO_ECC           0x00000010 /* do not use ECC */
+#define OTP_LOCK             0x00000020 /* sets page protection bit for page */
+#define OTP_ACCESS_READ      0x00001000
+#define OTP_ACCESS_READWRITE 0x00002000
+
+/* Return values for all functions */
+#define OTP_SUCCESS          0x00000000
+#define OTP_MASTER_ERROR     0x001
+#define OTP_WRITE_ERROR      0x003
+#define OTP_READ_ERROR       0x005
+#define OTP_ACC_VIO_ERROR    0x009
+#define OTP_DATA_MULT_ERROR  0x011
+#define OTP_ECC_MULT_ERROR   0x021
+#define OTP_PREV_WR_ERROR    0x041
+#define OTP_DATA_SB_WARN     0x100
+#define OTP_ECC_SB_WARN      0x200
+
+/**
+ *	bfin_otp_read - Read OTP pages
+ *
+ *	All reads must be in half page chunks (half page == 64 bits).
+ */
+ssize_t bfin_otp_read(struct file *file, char __user *buff, size_t count, loff_t *pos)
+{
+	ssize_t bytes_done;
+	u32 page, flags, ret;
+	u64 content;
+
+	stampit();
+
+	if (count % sizeof(u64))
+		return -EMSGSIZE;
+
+	if (mutex_lock_interruptible(&bfin_otp_lock))
+		return -ERESTARTSYS;
+
+	bytes_done = 0;
+	page = *pos / (sizeof(u64) * 2);
+	while (bytes_done < count) {
+		flags = (*pos % (sizeof(u64) * 2) ? OTP_UPPER_HALF : OTP_LOWER_HALF);
+		stamp("processing page %i (%s)", page, (flags == OTP_UPPER_HALF ? "upper" : "lower"));
+		ret = otp_read(page, flags, &content);
+		if (ret & OTP_MASTER_ERROR) {
+			bytes_done = -EIO;
+			break;
+		}
+		if (copy_to_user(buff + bytes_done, &content, sizeof(content))) {
+			bytes_done = -EFAULT;
+			break;
+		}
+		if (flags == OTP_UPPER_HALF)
+			++page;
+		bytes_done += sizeof(content);
+		*pos += sizeof(content);
+	}
+
+	mutex_unlock(&bfin_otp_lock);
+
+	return bytes_done;
+}
+
+#ifdef CONFIG_BFIN_OTP_WRITE_ENABLE
+/**
+ *	bfin_otp_write - Write OTP pages
+ *
+ *	All writes must be in half page chunks (half page == 64 bits).
+ */
+static ssize_t bfin_otp_write(struct file *filp, const char __user *buff, size_t count, loff_t *pos)
+{
+	stampit();
+
+	if (count % sizeof(u64))
+		return -EMSGSIZE;
+
+	if (mutex_lock_interruptible(&bfin_otp_lock))
+		return -ERESTARTSYS;
+
+	/* need otp_init() documentation before this can be implemented */
+
+	mutex_unlock(&bfin_otp_lock);
+
+	return -EINVAL;
+}
+#else
+# define bfin_otp_write NULL
+#endif
+
+static struct class *bfin_otp_class;
+static dev_t bfin_otp_dev_node;
+static struct cdev bfin_otp_cdev;
+
+static struct file_operations bfin_otp_fops = {
+	.owner    = THIS_MODULE,
+	.read     = bfin_otp_read,
+	.write    = bfin_otp_write,
+};
+
+/**
+ *	bfin_otp_init - Initialize module
+ *
+ *	Registers the device and notifier handler. Actual device
+ *	initialization is handled by bfin_otp_open().
+ */
+static int __init bfin_otp_init(void)
+{
+	int ret;
+
+	stampit();
+
+	ret = alloc_chrdev_region(&bfin_otp_dev_node, 0, 1, "otp");
+	if (ret) {
+		printk(KERN_ERR PFX "unable to get a char device\n");
+		return ret;
+	}
+
+	cdev_init(&bfin_otp_cdev, &bfin_otp_fops);
+	bfin_otp_cdev.owner = THIS_MODULE;
+	bfin_otp_cdev.ops = &bfin_otp_fops;
+
+	ret = cdev_add(&bfin_otp_cdev, bfin_otp_dev_node, 1);
+	if (ret) {
+		unregister_chrdev_region(bfin_otp_dev_node, 1);
+		printk(KERN_ERR PFX "unable to register char device\n");
+		return ret;
+	}
+
+	bfin_otp_class = class_create(THIS_MODULE, "otp");
+	device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
+
+	printk(KERN_INFO PFX "initialized\n");
+
+	return 0;
+}
+
+/**
+ *	bfin_otp_exit - Deinitialize module
+ *
+ *	Unregisters the device and notifier handler. Actual device
+ *	deinitialization is handled by bfin_otp_close().
+ */
+static void __exit bfin_otp_exit(void)
+{
+	stampit();
+
+	device_destroy(bfin_otp_class, bfin_otp_dev_node);
+	class_destroy(bfin_otp_class);
+	unregister_chrdev_region(bfin_otp_dev_node, 1);
+	cdev_del(&bfin_otp_cdev);
+}
+
+module_init(bfin_otp_init);
+module_exit(bfin_otp_exit);
+
+MODULE_AUTHOR("Mike Frysinger <vapier@gentoo.org>");
+MODULE_DESCRIPTION("Blackfin OTP Memory Interface");
+MODULE_LICENSE("GPL");
-- 
1.5.3.4

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 10:36 [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory Bryan Wu
@ 2008-01-30 11:00 ` Jiri Slaby
  2008-01-30 12:39   ` Robin Getz
                     ` (2 more replies)
  0 siblings, 3 replies; 11+ messages in thread
From: Jiri Slaby @ 2008-01-30 11:00 UTC (permalink / raw)
  To: Bryan Wu; +Cc: linux-kernel, Mike Frysinger

On 01/30/2008 11:36 AM, Bryan Wu wrote:
> From: Mike Frysinger <michael.frysinger@analog.com>
> 
> initial char driver for otp memory
> (only read supported atm ... needs real examples/docs for write support)
> 
> Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
> Signed-off-by: Bryan Wu <bryan.wu@analog.com>
> ---
>  drivers/char/Kconfig    |   28 +++++++
>  drivers/char/Makefile   |    1 +
>  drivers/char/bfin-otp.c |  203 +++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 232 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/char/bfin-otp.c
> 
[...]
> diff --git a/drivers/char/bfin-otp.c b/drivers/char/bfin-otp.c
> new file mode 100644
> index 0000000..896a987
> --- /dev/null
> +++ b/drivers/char/bfin-otp.c
> @@ -0,0 +1,203 @@
> +/*
> + * Blackfin On-Chip OTP Memory Interface
> + *  Supports BF52x/BF54x
> + *
> + * Copyright 2007-2008 Analog Devices Inc.
> + *
> + * Enter bugs at http://blackfin.uclinux.org/
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +
> +#include <linux/cdev.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/fs.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +
> +#include <asm/blackfin.h>
> +#include <asm/uaccess.h>
> +
> +#define stamp(fmt, args...) pr_debug("%s:%i: " fmt "\n", __func__, __LINE__, ## args)
> +#define stampit() stamp("here i am")
> +
> +#define DRIVER_NAME "bfin-otp"
> +#define PFX DRIVER_NAME ": "
> +
> +DEFINE_MUTEX(bfin_otp_lock);

static?

> +
> +/* OTP Boot ROM functions */
> +#define _BOOTROM_OTP_COMMAND           0xEF000018
> +#define _BOOTROM_OTP_READ              0xEF00001A
> +#define _BOOTROM_OTP_WRITE             0xEF00001C
[...]
> +/**
> + *	bfin_otp_init - Initialize module
> + *
> + *	Registers the device and notifier handler. Actual device
> + *	initialization is handled by bfin_otp_open().
> + */
> +static int __init bfin_otp_init(void)
> +{
> +	int ret;
> +
> +	stampit();
> +
> +	ret = alloc_chrdev_region(&bfin_otp_dev_node, 0, 1, "otp");
> +	if (ret) {
> +		printk(KERN_ERR PFX "unable to get a char device\n");
> +		return ret;
> +	}
> +
> +	cdev_init(&bfin_otp_cdev, &bfin_otp_fops);
> +	bfin_otp_cdev.owner = THIS_MODULE;
> +	bfin_otp_cdev.ops = &bfin_otp_fops;

You don't need to set the fops again.

> +
> +	ret = cdev_add(&bfin_otp_cdev, bfin_otp_dev_node, 1);
> +	if (ret) {
> +		unregister_chrdev_region(bfin_otp_dev_node, 1);
> +		printk(KERN_ERR PFX "unable to register char device\n");
> +		return ret;
> +	}
> +
> +	bfin_otp_class = class_create(THIS_MODULE, "otp");
> +	device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");

Anyway, wouldn't be easier/better to use misc.c functionality here 
(misc_register() et al.)?

> +
> +	printk(KERN_INFO PFX "initialized\n");
> +
> +	return 0;
> +}

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 11:00 ` Jiri Slaby
@ 2008-01-30 12:39   ` Robin Getz
  2008-01-30 13:08     ` Jiri Slaby
  2008-01-30 13:15     ` Bryan Wu
  2008-01-30 13:19   ` Mike Frysinger
  2008-02-05 18:59   ` Mike Frysinger
  2 siblings, 2 replies; 11+ messages in thread
From: Robin Getz @ 2008-01-30 12:39 UTC (permalink / raw)
  To: Jiri Slaby; +Cc: Bryan Wu, linux-kernel, Mike Frysinger

On Wed 30 Jan 2008 06:00, Jiri Slaby pondered:
> On 01/30/2008 11:36 AM, Bryan Wu wrote:
> > From: Mike Frysinger <michael.frysinger@analog.com>
> > 
> > initial char driver for otp memory
> > (only read supported atm ... needs real examples/docs for write support)
> > 
> > Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
> > Signed-off-by: Bryan Wu <bryan.wu@analog.com>

> > +	bfin_otp_class = class_create(THIS_MODULE, "otp");
> > +	device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
> 
> Anyway, wouldn't be easier/better to use misc.c functionality here 
> (misc_register() et al.)?

OTP (one time programmable) memory are not registers, they are small blocks 
(8k bytes) of non violate on chip memory, for storing things that you don't 
want other people to look at via a PCB level probe. (like keys), or things 
that are just helpful - like MAC addresses.

-Robin

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 12:39   ` Robin Getz
@ 2008-01-30 13:08     ` Jiri Slaby
  2008-01-30 13:15     ` Bryan Wu
  1 sibling, 0 replies; 11+ messages in thread
From: Jiri Slaby @ 2008-01-30 13:08 UTC (permalink / raw)
  To: Robin Getz; +Cc: Bryan Wu, linux-kernel, Mike Frysinger

On 01/30/2008 01:39 PM, Robin Getz wrote:
> On Wed 30 Jan 2008 06:00, Jiri Slaby pondered:
>> On 01/30/2008 11:36 AM, Bryan Wu wrote:
>>> From: Mike Frysinger <michael.frysinger@analog.com>
>>>
>>> initial char driver for otp memory
>>> (only read supported atm ... needs real examples/docs for write support)
>>>
>>> Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
>>> Signed-off-by: Bryan Wu <bryan.wu@analog.com>
> 
>>> +	bfin_otp_class = class_create(THIS_MODULE, "otp");
>>> +	device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
>> Anyway, wouldn't be easier/better to use misc.c functionality here 
>> (misc_register() et al.)?
> 
> OTP (one time programmable) memory are not registers, they are small blocks 
> (8k bytes) of non violate on chip memory, for storing things that you don't 
> want other people to look at via a PCB level probe. (like keys), or things 
> that are just helpful - like MAC addresses.

Sorry, misc_register() allows you to get rid of the chrdev initialization 
including class creation. Maybe I'm not understanding what you are trying to 
explain me?

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 12:39   ` Robin Getz
  2008-01-30 13:08     ` Jiri Slaby
@ 2008-01-30 13:15     ` Bryan Wu
  2008-01-30 13:43       ` Jiri Slaby
  1 sibling, 1 reply; 11+ messages in thread
From: Bryan Wu @ 2008-01-30 13:15 UTC (permalink / raw)
  To: Robin Getz; +Cc: Jiri Slaby, Bryan Wu, linux-kernel, Mike Frysinger

On Jan 30, 2008 8:39 PM, Robin Getz <rgetz@blackfin.uclinux.org> wrote:
> On Wed 30 Jan 2008 06:00, Jiri Slaby pondered:
> > On 01/30/2008 11:36 AM, Bryan Wu wrote:
> > > From: Mike Frysinger <michael.frysinger@analog.com>
> > >
> > > initial char driver for otp memory
> > > (only read supported atm ... needs real examples/docs for write support)
> > >
> > > Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
> > > Signed-off-by: Bryan Wu <bryan.wu@analog.com>
>
> > > +   bfin_otp_class = class_create(THIS_MODULE, "otp");
> > > +   device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
> >
> > Anyway, wouldn't be easier/better to use misc.c functionality here
> > (misc_register() et al.)?
>
> OTP (one time programmable) memory are not registers, they are small blocks
> (8k bytes) of non violate on chip memory, for storing things that you don't
> want other people to look at via a PCB level probe. (like keys), or things
> that are just helpful - like MAC addresses.
>

Jiri means this OTP char driver can use misc character driver
interface as misc_register().

And one question for Jiri, what is the difference between misc char
driver with other char drivers.
Because we got some other char drivers locally, maybe some day send them out.

Thanks
-Bryan

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 11:00 ` Jiri Slaby
  2008-01-30 12:39   ` Robin Getz
@ 2008-01-30 13:19   ` Mike Frysinger
  2008-01-30 13:38     ` Jiri Slaby
  2008-02-05 18:59   ` Mike Frysinger
  2 siblings, 1 reply; 11+ messages in thread
From: Mike Frysinger @ 2008-01-30 13:19 UTC (permalink / raw)
  To: Jiri Slaby; +Cc: Bryan Wu, linux-kernel, Mike Frysinger

On Jan 30, 2008 6:00 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
> On 01/30/2008 11:36 AM, Bryan Wu wrote:
> > +DEFINE_MUTEX(bfin_otp_lock);
>
> static?

the macro threw me ... fixed now, thanks

> > +static int __init bfin_otp_init(void)
> > +{
> > +     int ret;
> > +
> > +     stampit();
> > +
> > +     ret = alloc_chrdev_region(&bfin_otp_dev_node, 0, 1, "otp");
> > +     if (ret) {
> > +             printk(KERN_ERR PFX "unable to get a char device\n");
> > +             return ret;
> > +     }
> > +
> > +     cdev_init(&bfin_otp_cdev, &bfin_otp_fops);
> > +     bfin_otp_cdev.owner = THIS_MODULE;
> > +     bfin_otp_cdev.ops = &bfin_otp_fops;
>
> You don't need to set the fops again.

i did research this a bit but the information on the topic seemed
spotty and usage was inconsistent ... i guess recent things have
smartened up, so i'll drop the assignment

> > +     ret = cdev_add(&bfin_otp_cdev, bfin_otp_dev_node, 1);
> > +     if (ret) {
> > +             unregister_chrdev_region(bfin_otp_dev_node, 1);
> > +             printk(KERN_ERR PFX "unable to register char device\n");
> > +             return ret;
> > +     }
> > +
> > +     bfin_otp_class = class_create(THIS_MODULE, "otp");
> > +     device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
>
> Anyway, wouldn't be easier/better to use misc.c functionality here
> (misc_register() et al.)?

probably ... i just didnt want to statically allocate a number in the
range that would be Blackfin specific ...
-mike

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 13:19   ` Mike Frysinger
@ 2008-01-30 13:38     ` Jiri Slaby
  2008-01-30 13:41       ` Mike Frysinger
  0 siblings, 1 reply; 11+ messages in thread
From: Jiri Slaby @ 2008-01-30 13:38 UTC (permalink / raw)
  To: Mike Frysinger; +Cc: Bryan Wu, linux-kernel, Mike Frysinger

On 01/30/2008 02:19 PM, Mike Frysinger wrote:
> On Jan 30, 2008 6:00 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
>> On 01/30/2008 11:36 AM, Bryan Wu wrote:
>>> +     ret = cdev_add(&bfin_otp_cdev, bfin_otp_dev_node, 1);
>>> +     if (ret) {
>>> +             unregister_chrdev_region(bfin_otp_dev_node, 1);
>>> +             printk(KERN_ERR PFX "unable to register char device\n");
>>> +             return ret;
>>> +     }
>>> +
>>> +     bfin_otp_class = class_create(THIS_MODULE, "otp");
>>> +     device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
>> Anyway, wouldn't be easier/better to use misc.c functionality here
>> (misc_register() et al.)?
> 
> probably ... i just didnt want to statically allocate a number in the
> range that would be Blackfin specific ...

MISC_DYNAMIC_MINOR is definitely your friend ;).


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 13:38     ` Jiri Slaby
@ 2008-01-30 13:41       ` Mike Frysinger
  0 siblings, 0 replies; 11+ messages in thread
From: Mike Frysinger @ 2008-01-30 13:41 UTC (permalink / raw)
  To: Jiri Slaby; +Cc: Bryan Wu, linux-kernel, Mike Frysinger

On Jan 30, 2008 8:38 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
> On 01/30/2008 02:19 PM, Mike Frysinger wrote:
> > On Jan 30, 2008 6:00 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
> >> On 01/30/2008 11:36 AM, Bryan Wu wrote:
> >>> +     ret = cdev_add(&bfin_otp_cdev, bfin_otp_dev_node, 1);
> >>> +     if (ret) {
> >>> +             unregister_chrdev_region(bfin_otp_dev_node, 1);
> >>> +             printk(KERN_ERR PFX "unable to register char device\n");
> >>> +             return ret;
> >>> +     }
> >>> +
> >>> +     bfin_otp_class = class_create(THIS_MODULE, "otp");
> >>> +     device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
> >> Anyway, wouldn't be easier/better to use misc.c functionality here
> >> (misc_register() et al.)?
> >
> > probably ... i just didnt want to statically allocate a number in the
> > range that would be Blackfin specific ...
>
> MISC_DYNAMIC_MINOR is definitely your friend ;).

ah, great ... i'll check it out then, thanks
-mike

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 13:15     ` Bryan Wu
@ 2008-01-30 13:43       ` Jiri Slaby
  2008-01-30 13:53         ` Jiri Slaby
  0 siblings, 1 reply; 11+ messages in thread
From: Jiri Slaby @ 2008-01-30 13:43 UTC (permalink / raw)
  To: Bryan Wu; +Cc: Robin Getz, Bryan Wu, linux-kernel, Mike Frysinger

On 01/30/2008 02:15 PM, Bryan Wu wrote:
> And one question for Jiri, what is the difference between misc char
> driver with other char drivers.

No difference in behaviour. Open function in misc replaces fops by your 
specified one (like a v4l or tty layer, or chrdev_open aswell, which will be 
called on each character device open).

> Because we got some other char drivers locally, maybe some day send them out.

Misc has one predefined major and is used for such uses, in which you need only 
one minor number. The point is not to block resting 254 minors of one major just 
for only one minor used.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 13:43       ` Jiri Slaby
@ 2008-01-30 13:53         ` Jiri Slaby
  0 siblings, 0 replies; 11+ messages in thread
From: Jiri Slaby @ 2008-01-30 13:53 UTC (permalink / raw)
  To: Bryan Wu; +Cc: Robin Getz, Bryan Wu, linux-kernel, Mike Frysinger

On 01/30/2008 02:43 PM, Jiri Slaby wrote:
> specified one (like a v4l or tty layer, or chrdev_open aswell, which 

Eh, no, not the tty layer...

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory
  2008-01-30 11:00 ` Jiri Slaby
  2008-01-30 12:39   ` Robin Getz
  2008-01-30 13:19   ` Mike Frysinger
@ 2008-02-05 18:59   ` Mike Frysinger
  2 siblings, 0 replies; 11+ messages in thread
From: Mike Frysinger @ 2008-02-05 18:59 UTC (permalink / raw)
  To: Jiri Slaby; +Cc: Bryan Wu, linux-kernel, Mike Frysinger

On Jan 30, 2008 6:00 AM, Jiri Slaby <jirislaby@gmail.com> wrote:
> On 01/30/2008 11:36 AM, Bryan Wu wrote:
> > +
> > +     ret = cdev_add(&bfin_otp_cdev, bfin_otp_dev_node, 1);
> > +     if (ret) {
> > +             unregister_chrdev_region(bfin_otp_dev_node, 1);
> > +             printk(KERN_ERR PFX "unable to register char device\n");
> > +             return ret;
> > +     }
> > +
> > +     bfin_otp_class = class_create(THIS_MODULE, "otp");
> > +     device_create(bfin_otp_class, NULL, bfin_otp_dev_node, "otp");
>
> Anyway, wouldn't be easier/better to use misc.c functionality here
> (misc_register() et al.)?

thanks, ive converted this now ... Bryan can post an updated patch :)
http://blackfin.uclinux.org/gf/project/linux-kernel/scmsvn/?action=browse&path=/trunk/drivers/char/bfin-otp.c&r1=4224&r2=4223
-mike

^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2008-02-05 19:00 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2008-01-30 10:36 [PATCH 1/1] [Blackfin] char driver for Blackfin on-chip OTP memory Bryan Wu
2008-01-30 11:00 ` Jiri Slaby
2008-01-30 12:39   ` Robin Getz
2008-01-30 13:08     ` Jiri Slaby
2008-01-30 13:15     ` Bryan Wu
2008-01-30 13:43       ` Jiri Slaby
2008-01-30 13:53         ` Jiri Slaby
2008-01-30 13:19   ` Mike Frysinger
2008-01-30 13:38     ` Jiri Slaby
2008-01-30 13:41       ` Mike Frysinger
2008-02-05 18:59   ` Mike Frysinger

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