Revision aa9887608e77b835d51f05a54940380391cd4e21 authored by Anup Patel on 27 September 2020, 05:39:16 UTC, committed by Palmer Dabbelt on 30 September 2020, 18:05:14 UTC
The NoMMU kernel is broken for QEMU virt machine from Linux-5.9-rc6
because clint_time_val is used even before CLINT driver is probed
at following places:
1. rand_initialize() calls get_cycles() which in-turn uses
clint_time_val
2. boot_init_stack_canary() calls get_cycles() which in-turn
uses clint_time_val
The issue#1 (above) is fixed by providing custom random_get_entropy()
for RISC-V NoMMU kernel. For issue#2 (above), we remove dependency of
boot_init_stack_canary() on get_cycles() and this is aligned with the
boot_init_stack_canary() implementations of ARM, ARM64 and MIPS kernel.
Fixes: d5be89a8d118 ("RISC-V: Resurrect the MMIO timer implementation for M-mode systems")
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
1 parent c14decf
leds-lp5562.rst
========================
Kernel driver for lp5562
========================
* TI LP5562 LED Driver
Author: Milo(Woogyom) Kim <milo.kim@ti.com>
Description
===========
LP5562 can drive up to 4 channels. R/G/B and White.
LEDs can be controlled directly via the led class control interface.
All four channels can be also controlled using the engine micro programs.
LP5562 has the internal program memory for running various LED patterns.
For the details, please refer to 'firmware' section in leds-lp55xx.txt
Device attribute
================
engine_mux
3 Engines are allocated in LP5562, but the number of channel is 4.
Therefore each channel should be mapped to the engine number.
Value: RGB or W
This attribute is used for programming LED data with the firmware interface.
Unlike the LP5521/LP5523/55231, LP5562 has unique feature for the engine mux,
so additional sysfs is required
LED Map
===== === ===============================
Red ... Engine 1 (fixed)
Green ... Engine 2 (fixed)
Blue ... Engine 3 (fixed)
White ... Engine 1 or 2 or 3 (selective)
===== === ===============================
How to load the program data using engine_mux
=============================================
Before loading the LP5562 program data, engine_mux should be written between
the engine selection and loading the firmware.
Engine mux has two different mode, RGB and W.
RGB is used for loading RGB program data, W is used for W program data.
For example, run blinking green channel pattern::
echo 2 > /sys/bus/i2c/devices/xxxx/select_engine # 2 is for green channel
echo "RGB" > /sys/bus/i2c/devices/xxxx/engine_mux # engine mux for RGB
echo 1 > /sys/class/firmware/lp5562/loading
echo "4000600040FF6000" > /sys/class/firmware/lp5562/data
echo 0 > /sys/class/firmware/lp5562/loading
echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
To run a blinking white pattern::
echo 1 or 2 or 3 > /sys/bus/i2c/devices/xxxx/select_engine
echo "W" > /sys/bus/i2c/devices/xxxx/engine_mux
echo 1 > /sys/class/firmware/lp5562/loading
echo "4000600040FF6000" > /sys/class/firmware/lp5562/data
echo 0 > /sys/class/firmware/lp5562/loading
echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
How to load the predefined patterns
===================================
Please refer to 'leds-lp55xx.txt"
Setting Current of Each Channel
===============================
Like LP5521 and LP5523/55231, LP5562 provides LED current settings.
The 'led_current' and 'max_current' are used.
Example of Platform data
========================
::
static struct lp55xx_led_config lp5562_led_config[] = {
{
.name = "R",
.chan_nr = 0,
.led_current = 20,
.max_current = 40,
},
{
.name = "G",
.chan_nr = 1,
.led_current = 20,
.max_current = 40,
},
{
.name = "B",
.chan_nr = 2,
.led_current = 20,
.max_current = 40,
},
{
.name = "W",
.chan_nr = 3,
.led_current = 20,
.max_current = 40,
},
};
static int lp5562_setup(void)
{
/* setup HW resources */
}
static void lp5562_release(void)
{
/* Release HW resources */
}
static void lp5562_enable(bool state)
{
/* Control of chip enable signal */
}
static struct lp55xx_platform_data lp5562_platform_data = {
.led_config = lp5562_led_config,
.num_channels = ARRAY_SIZE(lp5562_led_config),
.setup_resources = lp5562_setup,
.release_resources = lp5562_release,
.enable = lp5562_enable,
};
To configure the platform specific data, lp55xx_platform_data structure is used
If the current is set to 0 in the platform data, that channel is
disabled and it is not visible in the sysfs.
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