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OMAP: hwmod: improve documentation, clean up function names
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This patch:

- adds more documentation to the hwmod code

- fixes some documentation typos elsewhere in the file

- changes the _sysc_*() function names to appear in (verb, noun) order,
  to match the rest of the function names.

This patch should not result in any functional change.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Benoît Cousson <b-cousson@ti.com>
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Paul Walmsley committed Sep 22, 2010
1 parent 4ef7aca commit 74ff3a6
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Showing 2 changed files with 123 additions and 29 deletions.
141 changes: 119 additions & 22 deletions arch/arm/mach-omap2/omap_hwmod.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,10 +13,102 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This code manages "OMAP modules" (on-chip devices) and their
* integration with Linux device driver and bus code.
*
* References:
* Introduction
* ------------
* One way to view an OMAP SoC is as a collection of largely unrelated
* IP blocks connected by interconnects. The IP blocks include
* devices such as ARM processors, audio serial interfaces, UARTs,
* etc. Some of these devices, like the DSP, are created by TI;
* others, like the SGX, largely originate from external vendors. In
* TI's documentation, on-chip devices are referred to as "OMAP
* modules." Some of these IP blocks are identical across several
* OMAP versions. Others are revised frequently.
*
* These OMAP modules are tied together by various interconnects.
* Most of the address and data flow between modules is via OCP-based
* interconnects such as the L3 and L4 buses; but there are other
* interconnects that distribute the hardware clock tree, handle idle
* and reset signaling, supply power, and connect the modules to
* various pads or balls on the OMAP package.
*
* OMAP hwmod provides a consistent way to describe the on-chip
* hardware blocks and their integration into the rest of the chip.
* This description can be automatically generated from the TI
* hardware database. OMAP hwmod provides a standard, consistent API
* to reset, enable, idle, and disable these hardware blocks. And
* hwmod provides a way for other core code, such as the Linux device
* code or the OMAP power management and address space mapping code,
* to query the hardware database.
*
* Using hwmod
* -----------
* Drivers won't call hwmod functions directly. That is done by the
* omap_device code, and in rare occasions, by custom integration code
* in arch/arm/ *omap*. The omap_device code includes functions to
* build a struct platform_device using omap_hwmod data, and that is
* currently how hwmod data is communicated to drivers and to the
* Linux driver model. Most drivers will call omap_hwmod functions only
* indirectly, via pm_runtime*() functions.
*
* From a layering perspective, here is where the OMAP hwmod code
* fits into the kernel software stack:
*
* +-------------------------------+
* | Device driver code |
* | (e.g., drivers/) |
* +-------------------------------+
* | Linux driver model |
* | (platform_device / |
* | platform_driver data/code) |
* +-------------------------------+
* | OMAP core-driver integration |
* |(arch/arm/mach-omap2/devices.c)|
* +-------------------------------+
* | omap_device code |
* | (../plat-omap/omap_device.c) |
* +-------------------------------+
* ----> | omap_hwmod code/data | <-----
* | (../mach-omap2/omap_hwmod*) |
* +-------------------------------+
* | OMAP clock/PRCM/register fns |
* | (__raw_{read,write}l, clk*) |
* +-------------------------------+
*
* Device drivers should not contain any OMAP-specific code or data in
* them. They should only contain code to operate the IP block that
* the driver is responsible for. This is because these IP blocks can
* also appear in other SoCs, either from TI (such as DaVinci) or from
* other manufacturers; and drivers should be reusable across other
* platforms.
*
* The OMAP hwmod code also will attempt to reset and idle all on-chip
* devices upon boot. The goal here is for the kernel to be
* completely self-reliant and independent from bootloaders. This is
* to ensure a repeatable configuration, both to ensure consistent
* runtime behavior, and to make it easier for others to reproduce
* bugs.
*
* OMAP module activity states
* ---------------------------
* The hwmod code considers modules to be in one of several activity
* states. IP blocks start out in an UNKNOWN state, then once they
* are registered via the hwmod code, proceed to the REGISTERED state.
* Once their clock names are resolved to clock pointers, the module
* enters the CLKS_INITED state; and finally, once the module has been
* reset and the integration registers programmed, the INITIALIZED state
* is entered. The hwmod code will then place the module into either
* the IDLE state to save power, or in the case of a critical system
* module, the ENABLED state.
*
* OMAP core integration code can then call omap_hwmod*() functions
* directly to move the module between the IDLE, ENABLED, and DISABLED
* states, as needed. This is done during both the PM idle loop, and
* in the OMAP core integration code's implementation of the PM runtime
* functions.
*
* References
* ----------
* This is a partial list.
* - OMAP2420 Multimedia Processor Silicon Revision 2.1.1, 2.2 (SWPU064)
* - OMAP2430 Multimedia Device POP Silicon Revision 2.1 (SWPU090)
* - OMAP34xx Multimedia Device Silicon Revision 3.1 (SWPU108)
Expand Down Expand Up @@ -654,15 +746,15 @@ static void __iomem *_find_mpu_rt_base(struct omap_hwmod *oh, u8 index)
}

/**
* _sysc_enable - try to bring a module out of idle via OCP_SYSCONFIG
* _enable_sysc - try to bring a module out of idle via OCP_SYSCONFIG
* @oh: struct omap_hwmod *
*
* If module is marked as SWSUP_SIDLE, force the module out of slave
* idle; otherwise, configure it for smart-idle. If module is marked
* as SWSUP_MSUSPEND, force the module out of master standby;
* otherwise, configure it for smart-standby. No return value.
*/
static void _sysc_enable(struct omap_hwmod *oh)
static void _enable_sysc(struct omap_hwmod *oh)
{
u8 idlemode, sf;
u32 v;
Expand Down Expand Up @@ -708,15 +800,15 @@ static void _sysc_enable(struct omap_hwmod *oh)
}

/**
* _sysc_idle - try to put a module into idle via OCP_SYSCONFIG
* _idle_sysc - try to put a module into idle via OCP_SYSCONFIG
* @oh: struct omap_hwmod *
*
* If module is marked as SWSUP_SIDLE, force the module into slave
* idle; otherwise, configure it for smart-idle. If module is marked
* as SWSUP_MSUSPEND, force the module into master standby; otherwise,
* configure it for smart-standby. No return value.
*/
static void _sysc_idle(struct omap_hwmod *oh)
static void _idle_sysc(struct omap_hwmod *oh)
{
u8 idlemode, sf;
u32 v;
Expand All @@ -743,13 +835,13 @@ static void _sysc_idle(struct omap_hwmod *oh)
}

/**
* _sysc_shutdown - force a module into idle via OCP_SYSCONFIG
* _shutdown_sysc - force a module into idle via OCP_SYSCONFIG
* @oh: struct omap_hwmod *
*
* Force the module into slave idle and master suspend. No return
* value.
*/
static void _sysc_shutdown(struct omap_hwmod *oh)
static void _shutdown_sysc(struct omap_hwmod *oh)
{
u32 v;
u8 sf;
Expand Down Expand Up @@ -1071,8 +1163,11 @@ static int _reset(struct omap_hwmod *oh)
* @oh: struct omap_hwmod *
*
* Enables an omap_hwmod @oh such that the MPU can access the hwmod's
* register target. Returns -EINVAL if the hwmod is in the wrong
* state or passes along the return value of _wait_target_ready().
* register target. (This function has a full name --
* _omap_hwmod_enable() rather than simply _enable() -- because it is
* currently required by the pm34xx.c idle loop.) Returns -EINVAL if
* the hwmod is in the wrong state or passes along the return value of
* _wait_target_ready().
*/
int _omap_hwmod_enable(struct omap_hwmod *oh)
{
Expand Down Expand Up @@ -1110,7 +1205,7 @@ int _omap_hwmod_enable(struct omap_hwmod *oh)
if (oh->class->sysc) {
if (!(oh->_int_flags & _HWMOD_SYSCONFIG_LOADED))
_update_sysc_cache(oh);
_sysc_enable(oh);
_enable_sysc(oh);
}
} else {
pr_debug("omap_hwmod: %s: _wait_target_ready: %d\n",
Expand All @@ -1121,12 +1216,14 @@ int _omap_hwmod_enable(struct omap_hwmod *oh)
}

/**
* _idle - idle an omap_hwmod
* _omap_hwmod_idle - idle an omap_hwmod
* @oh: struct omap_hwmod *
*
* Idles an omap_hwmod @oh. This should be called once the hwmod has
* no further work. Returns -EINVAL if the hwmod is in the wrong
* state or returns 0.
* no further work. (This function has a full name --
* _omap_hwmod_idle() rather than simply _idle() -- because it is
* currently required by the pm34xx.c idle loop.) Returns -EINVAL if
* the hwmod is in the wrong state or returns 0.
*/
int _omap_hwmod_idle(struct omap_hwmod *oh)
{
Expand All @@ -1139,7 +1236,7 @@ int _omap_hwmod_idle(struct omap_hwmod *oh)
pr_debug("omap_hwmod: %s: idling\n", oh->name);

if (oh->class->sysc)
_sysc_idle(oh);
_idle_sysc(oh);
_del_initiator_dep(oh, mpu_oh);
_disable_clocks(oh);

Expand Down Expand Up @@ -1169,7 +1266,7 @@ static int _shutdown(struct omap_hwmod *oh)
pr_debug("omap_hwmod: %s: disabling\n", oh->name);

if (oh->class->sysc)
_sysc_shutdown(oh);
_shutdown_sysc(oh);

/*
* If an IP contains only one HW reset line, then assert it
Expand Down Expand Up @@ -1262,7 +1359,7 @@ static int _setup(struct omap_hwmod *oh, void *data)
*/
if (oh->class->sysc) {
_update_sysc_cache(oh);
_sysc_enable(oh);
_enable_sysc(oh);
}
}

Expand Down Expand Up @@ -1518,7 +1615,7 @@ int omap_hwmod_unregister(struct omap_hwmod *oh)
* omap_hwmod_enable - enable an omap_hwmod
* @oh: struct omap_hwmod *
*
* Enable an omap_hwomd @oh. Intended to be called by omap_device_enable().
* Enable an omap_hwmod @oh. Intended to be called by omap_device_enable().
* Returns -EINVAL on error or passes along the return value from _enable().
*/
int omap_hwmod_enable(struct omap_hwmod *oh)
Expand All @@ -1540,7 +1637,7 @@ int omap_hwmod_enable(struct omap_hwmod *oh)
* omap_hwmod_idle - idle an omap_hwmod
* @oh: struct omap_hwmod *
*
* Idle an omap_hwomd @oh. Intended to be called by omap_device_idle().
* Idle an omap_hwmod @oh. Intended to be called by omap_device_idle().
* Returns -EINVAL on error or passes along the return value from _idle().
*/
int omap_hwmod_idle(struct omap_hwmod *oh)
Expand All @@ -1559,7 +1656,7 @@ int omap_hwmod_idle(struct omap_hwmod *oh)
* omap_hwmod_shutdown - shutdown an omap_hwmod
* @oh: struct omap_hwmod *
*
* Shutdown an omap_hwomd @oh. Intended to be called by
* Shutdown an omap_hwmod @oh. Intended to be called by
* omap_device_shutdown(). Returns -EINVAL on error or passes along
* the return value from _shutdown().
*/
Expand Down
11 changes: 4 additions & 7 deletions arch/arm/plat-omap/include/plat/omap_hwmod.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,19 +14,16 @@
*
* These headers and macros are used to define OMAP on-chip module
* data and their integration with other OMAP modules and Linux.
*
* References:
* - OMAP2420 Multimedia Processor Silicon Revision 2.1.1, 2.2 (SWPU064)
* - OMAP2430 Multimedia Device POP Silicon Revision 2.1 (SWPU090)
* - OMAP34xx Multimedia Device Silicon Revision 3.1 (SWPU108)
* - OMAP4430 Multimedia Device Silicon Revision 1.0 (SWPU140)
* - Open Core Protocol Specification 2.2
* Copious documentation and references can also be found in the
* omap_hwmod code, in arch/arm/mach-omap2/omap_hwmod.c (as of this
* writing).
*
* To do:
* - add interconnect error log structures
* - add pinmuxing
* - init_conn_id_bit (CONNID_BIT_VECTOR)
* - implement default hwmod SMS/SDRC flags?
* - remove unused fields
*
*/
#ifndef __ARCH_ARM_PLAT_OMAP_INCLUDE_MACH_OMAP_HWMOD_H
Expand Down

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