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Commit d3cb06e0 authored by Anshuman Khandual's avatar Anshuman Khandual Committed by Michael Ellerman
Browse files

powerpc/dscr: Add some in-code documentation 



This patch adds some in-code documentation to the DSCR related code to
make it more readable without having any functional change to it.

Signed-off-by: default avatarAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 1db36525

arch/powerpc/include/asm/processor.h

+9 −0
Original line number Diff line number Diff line
@@ -295,6 +295,15 @@ struct thread_struct { 
#endif

#ifdef CONFIG_PPC64

	unsigned long	dscr;

	/*

	 * This member element dscr_inherit indicates that the process

	 * has explicitly attempted and changed the DSCR register value

	 * for itself. Hence kernel wont use the default CPU DSCR value

	 * contained in the PACA structure anymore during process context

	 * switch. Once this variable is set, this behaviour will also be

	 * inherited to all the children of this process from that point

	 * onwards.

	 */

	int		dscr_inherit;

	unsigned long	ppr;	/* used to save/restore SMT priority */

#endif

arch/powerpc/kernel/sysfs.c

+38 −0
Original line number Diff line number Diff line
@@ -496,13 +496,34 @@ static DEVICE_ATTR(spurr, 0400, show_spurr, NULL); 
static DEVICE_ATTR(purr, 0400, show_purr, store_purr);

static DEVICE_ATTR(pir, 0400, show_pir, NULL);



/*

 * This is the system wide DSCR register default value. Any

 * change to this default value through the sysfs interface

 * will update all per cpu DSCR default values across the

 * system stored in their respective PACA structures.

 */

static unsigned long dscr_default;



/**

 * read_dscr() - Fetch the cpu specific DSCR default

 * @val:	Returned cpu specific DSCR default value

 *

 * This function returns the per cpu DSCR default value

 * for any cpu which is contained in it's PACA structure.

 */

static void read_dscr(void *val)

{

	*(unsigned long *)val = get_paca()->dscr_default;

}





/**

 * write_dscr() - Update the cpu specific DSCR default

 * @val:	New cpu specific DSCR default value to update

 *

 * This function updates the per cpu DSCR default value

 * for any cpu which is contained in it's PACA structure.

 */

static void write_dscr(void *val)

{

	get_paca()->dscr_default = *(unsigned long *)val;
@@ -520,12 +541,29 @@ static void add_write_permission_dev_attr(struct device_attribute *attr) 
	attr->attr.mode |= 0200;

}



/**

 * show_dscr_default() - Fetch the system wide DSCR default

 * @dev:	Device structure

 * @attr:	Device attribute structure

 * @buf:	Interface buffer

 *

 * This function returns the system wide DSCR default value.

 */

static ssize_t show_dscr_default(struct device *dev,

		struct device_attribute *attr, char *buf)

{

	return sprintf(buf, "%lx\n", dscr_default);

}



/**

 * store_dscr_default() - Update the system wide DSCR default

 * @dev:	Device structure

 * @attr:	Device attribute structure

 * @buf:	Interface buffer

 * @count:	Size of the update

 *

 * This function updates the system wide DSCR default value.

 */

static ssize_t __used store_dscr_default(struct device *dev,

		struct device_attribute *attr, const char *buf,

		size_t count)