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-lp5521.rst
========================
Kernel driver for lp5521
========================
* National Semiconductor LP5521 led driver chip
* Datasheet: http://www.national.com/pf/LP/LP5521.html
Authors: Mathias Nyman, Yuri Zaporozhets, Samu Onkalo
Contact: Samu Onkalo (samu.p.onkalo-at-nokia.com)
Description
-----------
LP5521 can drive up to 3 channels. Leds can be controlled directly via
the led class control interface. Channels have generic names:
lp5521:channelx, where x is 0 .. 2
All three channels can be also controlled using the engine micro programs.
More details of the instructions can be found from the public data sheet.
LP5521 has the internal program memory for running various LED patterns.
There are two ways to run LED patterns.
1) Legacy interface - enginex_mode and enginex_load
Control interface for the engines:
x is 1 .. 3
enginex_mode:
disabled, load, run
enginex_load:
store program (visible only in engine load mode)
Example (start to blink the channel 2 led)::
cd /sys/class/leds/lp5521:channel2/device
echo "load" > engine3_mode
echo "037f4d0003ff6000" > engine3_load
echo "run" > engine3_mode
To stop the engine::
echo "disabled" > engine3_mode
2) Firmware interface - LP55xx common interface
For the details, please refer to 'firmware' section in leds-lp55xx.txt
sysfs contains a selftest entry.
The test communicates with the chip and checks that
the clock mode is automatically set to the requested one.
Each channel has its own led current settings.
- /sys/class/leds/lp5521:channel0/led_current - RW
- /sys/class/leds/lp5521:channel0/max_current - RO
Format: 10x mA i.e 10 means 1.0 mA
example platform data::
static struct lp55xx_led_config lp5521_led_config[] = {
{
.name = "red",
.chan_nr = 0,
.led_current = 50,
.max_current = 130,
}, {
.name = "green",
.chan_nr = 1,
.led_current = 0,
.max_current = 130,
}, {
.name = "blue",
.chan_nr = 2,
.led_current = 0,
.max_current = 130,
}
};
static int lp5521_setup(void)
{
/* setup HW resources */
}
static void lp5521_release(void)
{
/* Release HW resources */
}
static void lp5521_enable(bool state)
{
/* Control of chip enable signal */
}
static struct lp55xx_platform_data lp5521_platform_data = {
.led_config = lp5521_led_config,
.num_channels = ARRAY_SIZE(lp5521_led_config),
.clock_mode = LP55XX_CLOCK_EXT,
.setup_resources = lp5521_setup,
.release_resources = lp5521_release,
.enable = lp5521_enable,
};
Note:
chan_nr can have values between 0 and 2.
The name of each channel can be configurable.
If the name field is not defined, the default name will be set to 'xxxx:channelN'
(XXXX : pdata->label or i2c client name, N : channel number)
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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