diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/arm/OMAP/omap_pm | 129 | ||||
| -rw-r--r-- | Documentation/cpu-freq/user-guide.txt | 9 | ||||
| -rw-r--r-- | Documentation/hwmon/wm831x | 37 | ||||
| -rw-r--r-- | Documentation/hwmon/wm8350 | 26 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 2 |
5 files changed, 200 insertions, 3 deletions
diff --git a/Documentation/arm/OMAP/omap_pm b/Documentation/arm/OMAP/omap_pm new file mode 100644 index 000000000000..5389440aade3 --- /dev/null +++ b/Documentation/arm/OMAP/omap_pm @@ -0,0 +1,129 @@ + +The OMAP PM interface +===================== + +This document describes the temporary OMAP PM interface. Driver +authors use these functions to communicate minimum latency or +throughput constraints to the kernel power management code. +Over time, the intention is to merge features from the OMAP PM +interface into the Linux PM QoS code. + +Drivers need to express PM parameters which: + +- support the range of power management parameters present in the TI SRF; + +- separate the drivers from the underlying PM parameter + implementation, whether it is the TI SRF or Linux PM QoS or Linux + latency framework or something else; + +- specify PM parameters in terms of fundamental units, such as + latency and throughput, rather than units which are specific to OMAP + or to particular OMAP variants; + +- allow drivers which are shared with other architectures (e.g., + DaVinci) to add these constraints in a way which won't affect non-OMAP + systems, + +- can be implemented immediately with minimal disruption of other + architectures. + + +This document proposes the OMAP PM interface, including the following +five power management functions for driver code: + +1. Set the maximum MPU wakeup latency: + (*pdata->set_max_mpu_wakeup_lat)(struct device *dev, unsigned long t) + +2. Set the maximum device wakeup latency: + (*pdata->set_max_dev_wakeup_lat)(struct device *dev, unsigned long t) + +3. Set the maximum system DMA transfer start latency (CORE pwrdm): + (*pdata->set_max_sdma_lat)(struct device *dev, long t) + +4. Set the minimum bus throughput needed by a device: + (*pdata->set_min_bus_tput)(struct device *dev, u8 agent_id, unsigned long r) + +5. Return the number of times the device has lost context + (*pdata->get_dev_context_loss_count)(struct device *dev) + + +Further documentation for all OMAP PM interface functions can be +found in arch/arm/plat-omap/include/mach/omap-pm.h. + + +The OMAP PM layer is intended to be temporary +--------------------------------------------- + +The intention is that eventually the Linux PM QoS layer should support +the range of power management features present in OMAP3. As this +happens, existing drivers using the OMAP PM interface can be modified +to use the Linux PM QoS code; and the OMAP PM interface can disappear. + + +Driver usage of the OMAP PM functions +------------------------------------- + +As the 'pdata' in the above examples indicates, these functions are +exposed to drivers through function pointers in driver .platform_data +structures. The function pointers are initialized by the board-*.c +files to point to the corresponding OMAP PM functions: +.set_max_dev_wakeup_lat will point to +omap_pm_set_max_dev_wakeup_lat(), etc. Other architectures which do +not support these functions should leave these function pointers set +to NULL. Drivers should use the following idiom: + + if (pdata->set_max_dev_wakeup_lat) + (*pdata->set_max_dev_wakeup_lat)(dev, t); + +The most common usage of these functions will probably be to specify +the maximum time from when an interrupt occurs, to when the device +becomes accessible. To accomplish this, driver writers should use the +set_max_mpu_wakeup_lat() function to to constrain the MPU wakeup +latency, and the set_max_dev_wakeup_lat() function to constrain the +device wakeup latency (from clk_enable() to accessibility). For +example, + + /* Limit MPU wakeup latency */ + if (pdata->set_max_mpu_wakeup_lat) + (*pdata->set_max_mpu_wakeup_lat)(dev, tc); + + /* Limit device powerdomain wakeup latency */ + if (pdata->set_max_dev_wakeup_lat) + (*pdata->set_max_dev_wakeup_lat)(dev, td); + + /* total wakeup latency in this example: (tc + td) */ + +The PM parameters can be overwritten by calling the function again +with the new value. The settings can be removed by calling the +function with a t argument of -1 (except in the case of +set_max_bus_tput(), which should be called with an r argument of 0). + +The fifth function above, omap_pm_get_dev_context_loss_count(), +is intended as an optimization to allow drivers to determine whether the +device has lost its internal context. If context has been lost, the +driver must restore its internal context before proceeding. + + +Other specialized interface functions +------------------------------------- + +The five functions listed above are intended to be usable by any +device driver. DSPBridge and CPUFreq have a few special requirements. +DSPBridge expresses target DSP performance levels in terms of OPP IDs. +CPUFreq expresses target MPU performance levels in terms of MPU +frequency. The OMAP PM interface contains functions for these +specialized cases to convert that input information (OPPs/MPU +frequency) into the form that the underlying power management +implementation needs: + +6. (*pdata->dsp_get_opp_table)(void) + +7. (*pdata->dsp_set_min_opp)(u8 opp_id) + +8. (*pdata->dsp_get_opp)(void) + +9. (*pdata->cpu_get_freq_table)(void) + +10. (*pdata->cpu_set_freq)(unsigned long f) + +11. (*pdata->cpu_get_freq)(void) diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt index 5d5f5fadd1c2..2a5b850847c0 100644 --- a/Documentation/cpu-freq/user-guide.txt +++ b/Documentation/cpu-freq/user-guide.txt @@ -176,7 +176,9 @@ scaling_governor, and by "echoing" the name of another work on some specific architectures or processors. -cpuinfo_cur_freq : Current speed of the CPU, in KHz. +cpuinfo_cur_freq : Current frequency of the CPU as obtained from + the hardware, in KHz. This is the frequency + the CPU actually runs at. scaling_available_frequencies : List of available frequencies, in KHz. @@ -196,7 +198,10 @@ related_cpus : List of CPUs that need some sort of frequency scaling_driver : Hardware driver for cpufreq. -scaling_cur_freq : Current frequency of the CPU, in KHz. +scaling_cur_freq : Current frequency of the CPU as determined by + the governor and cpufreq core, in KHz. This is + the frequency the kernel thinks the CPU runs + at. If you have selected the "userspace" governor which allows you to set the CPU operating frequency to a specific value, you can read out diff --git a/Documentation/hwmon/wm831x b/Documentation/hwmon/wm831x new file mode 100644 index 000000000000..24f47d8f6a42 --- /dev/null +++ b/Documentation/hwmon/wm831x @@ -0,0 +1,37 @@ +Kernel driver wm831x-hwmon +========================== + +Supported chips: + * Wolfson Microelectronics WM831x PMICs + Prefix: 'wm831x' + Datasheet: + http://www.wolfsonmicro.com/products/WM8310 + http://www.wolfsonmicro.com/products/WM8311 + http://www.wolfsonmicro.com/products/WM8312 + +Authors: Mark Brown <broonie@opensource.wolfsonmicro.com> + +Description +----------- + +The WM831x series of PMICs include an AUXADC which can be used to +monitor a range of system operating parameters, including the voltages +of the major supplies within the system. Currently the driver provides +reporting of all the input values but does not provide any alarms. + +Voltage Monitoring +------------------ + +Voltages are sampled by a 12 bit ADC. Voltages in milivolts are 1.465 +times the ADC value. + +Temperature Monitoring +---------------------- + +Temperatures are sampled by a 12 bit ADC. Chip and battery temperatures +are available. The chip temperature is calculated as: + + Degrees celsius = (512.18 - data) / 1.0983 + +while the battery temperature calculation will depend on the NTC +thermistor component. diff --git a/Documentation/hwmon/wm8350 b/Documentation/hwmon/wm8350 new file mode 100644 index 000000000000..98f923bd2e92 --- /dev/null +++ b/Documentation/hwmon/wm8350 @@ -0,0 +1,26 @@ +Kernel driver wm8350-hwmon +========================== + +Supported chips: + * Wolfson Microelectronics WM835x PMICs + Prefix: 'wm8350' + Datasheet: + http://www.wolfsonmicro.com/products/WM8350 + http://www.wolfsonmicro.com/products/WM8351 + http://www.wolfsonmicro.com/products/WM8352 + +Authors: Mark Brown <broonie@opensource.wolfsonmicro.com> + +Description +----------- + +The WM835x series of PMICs include an AUXADC which can be used to +monitor a range of system operating parameters, including the voltages +of the major supplies within the system. Currently the driver provides +simple access to these major supplies. + +Voltage Monitoring +------------------ + +Voltages are sampled by a 12 bit ADC. For the internal supplies the ADC +is referenced to the system VRTC. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f45d0d8e71d8..0f17d16dc101 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1565,7 +1565,7 @@ and is between 256 and 4096 characters. It is defined in the file of returning the full 64-bit number. The default is to return 64-bit inode numbers. - nmi_debug= [KNL,AVR32] Specify one or more actions to take + nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take when a NMI is triggered. Format: [state][,regs][,debounce][,die] |