x86: Add low-power subsystem (lpss) support

This subsystem is present on various Intel SoCs.

Add very basic support for taking an lpss device out of reset.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
This commit is contained in:
Simon Glass 2019-12-06 21:42:52 -07:00 committed by Bin Meng
parent e556d3d630
commit b84d4d0932
3 changed files with 81 additions and 0 deletions

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@ -19,6 +19,7 @@ endif
obj-y += cpu.o
obj-y += fast_spi.o
obj-y += lpc.o
obj-y += lpss.o
ifndef CONFIG_TARGET_EFI_APP
obj-$(CONFIG_$(SPL_TPL_)X86_32BIT_INIT) += microcode.o
ifndef CONFIG_$(SPL_)X86_64

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@ -0,0 +1,44 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Special driver to handle of-platdata
*
* Copyright 2019 Google LLC
*
* Some code from coreboot lpss.c
*/
#include <common.h>
#include <dm.h>
#include <pci.h>
#include <asm/io.h>
#include <asm/lpss.h>
enum {
LPSS_RESET_CTL_REG = 0x204,
/*
* Bit 1:0 controls LPSS controller reset.
*
* 00 ->LPSS Host Controller is in reset (Reset Asserted)
* 01/10 ->Reserved
* 11 ->LPSS Host Controller is NOT at reset (Reset Released)
*/
LPSS_CNT_RST_RELEASE = 3,
/* Power management control and status register */
PME_CTRL_STATUS = 0x84,
/* Bit 1:0 Powerstate, controls D0 and D3 state */
POWER_STATE_MASK = 3,
};
/* Take controller out of reset */
void lpss_reset_release(void *regs)
{
writel(LPSS_CNT_RST_RELEASE, regs + LPSS_RESET_CTL_REG);
}
void lpss_set_power_state(struct udevice *dev, enum lpss_pwr_state state)
{
dm_pci_clrset_config8(dev, PME_CTRL_STATUS, POWER_STATE_MASK, state);
}

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@ -0,0 +1,36 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright 2019 Google LLC
*/
#ifndef __ASM_LPSS_H
#define __ASM_LPSS_H
struct udevice;
/* D0 and D3 enable config */
enum lpss_pwr_state {
STATE_D0 = 0,
STATE_D3 = 3
};
/**
* lpss_reset_release() - Release device from reset
*
* This is used for devices which have LPSS support.
*
* @regs: Pointer to device registers
*/
void lpss_reset_release(void *regs);
/**
* lpss_set_power_state() - Change power state of a device
*
* This is used for devices which have LPSS support.
*
* @dev: Device to update
* @state: New power state to set
*/
void lpss_set_power_state(struct udevice *dev, enum lpss_pwr_state state);
#endif