1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * CPU idle for DaVinci SoCs
4 *
5 * Copyright (C) 2009 Texas Instruments Incorporated. https://www.ti.com/
6 *
7 * Derived from Marvell Kirkwood CPU idle code
8 * (arch/arm/mach-kirkwood/cpuidle.c)
9 */
10
11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/platform_device.h>
14#include <linux/cpuidle.h>
15#include <linux/io.h>
16#include <linux/export.h>
17#include <asm/cpuidle.h>
18
19#include "cpuidle.h"
20#include "ddr2.h"
21
22#define DAVINCI_CPUIDLE_MAX_STATES 2
23
24static void __iomem *ddr2_reg_base;
25static bool ddr2_pdown;
26
27static void davinci_save_ddr_power(int enter, bool pdown)
28{
29 u32 val;
30
31 val = __raw_readl(addr: ddr2_reg_base + DDR2_SDRCR_OFFSET);
32
33 if (enter) {
34 if (pdown)
35 val |= DDR2_SRPD_BIT;
36 else
37 val &= ~DDR2_SRPD_BIT;
38 val |= DDR2_LPMODEN_BIT;
39 } else {
40 val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
41 }
42
43 __raw_writel(val, addr: ddr2_reg_base + DDR2_SDRCR_OFFSET);
44}
45
46/* Actual code that puts the SoC in different idle states */
47static __cpuidle int davinci_enter_idle(struct cpuidle_device *dev,
48 struct cpuidle_driver *drv, int index)
49{
50 davinci_save_ddr_power(enter: 1, pdown: ddr2_pdown);
51 cpu_do_idle();
52 davinci_save_ddr_power(enter: 0, pdown: ddr2_pdown);
53
54 return index;
55}
56
57static struct cpuidle_driver davinci_idle_driver = {
58 .name = "cpuidle-davinci",
59 .owner = THIS_MODULE,
60 .states[0] = ARM_CPUIDLE_WFI_STATE,
61 .states[1] = {
62 .enter = davinci_enter_idle,
63 .exit_latency = 10,
64 .target_residency = 10000,
65 .name = "DDR SR",
66 .desc = "WFI and DDR Self Refresh",
67 },
68 .state_count = DAVINCI_CPUIDLE_MAX_STATES,
69};
70
71static int __init davinci_cpuidle_probe(struct platform_device *pdev)
72{
73 struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
74
75 if (!pdata) {
76 dev_err(&pdev->dev, "cannot get platform data\n");
77 return -ENOENT;
78 }
79
80 ddr2_reg_base = pdata->ddr2_ctlr_base;
81
82 ddr2_pdown = pdata->ddr2_pdown;
83
84 return cpuidle_register(drv: &davinci_idle_driver, NULL);
85}
86
87static struct platform_driver davinci_cpuidle_driver = {
88 .driver = {
89 .name = "cpuidle-davinci",
90 },
91};
92
93static int __init davinci_cpuidle_init(void)
94{
95 return platform_driver_probe(&davinci_cpuidle_driver,
96 davinci_cpuidle_probe);
97}
98device_initcall(davinci_cpuidle_init);
99
100

source code of linux/arch/arm/mach-davinci/cpuidle.c