linux/drivers/power/reset/at91-sama5d2_shdwc.c

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/*
* Atmel SAMA5D2-Compatible Shutdown Controller (SHDWC) driver.
* Found on some SoCs as the sama5d2 (obviously).
*
* Copyright (C) 2015 Atmel Corporation,
* Nicolas Ferre <nicolas.ferre@atmel.com>
*
* Evolved from driver at91-poweroff.c.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*
* TODO:
* - addition to status of other wake-up inputs [1 - 15]
* - Analog Comparator wake-up alarm
* - Serial RX wake-up alarm
* - low power debouncer
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#define SLOW_CLOCK_FREQ 32768
#define AT91_SHDW_CR 0x00 /* Shut Down Control Register */
#define AT91_SHDW_SHDW BIT(0) /* Shut Down command */
#define AT91_SHDW_KEY (0xa5UL << 24) /* KEY Password */
#define AT91_SHDW_MR 0x04 /* Shut Down Mode Register */
#define AT91_SHDW_WKUPDBC_SHIFT 24
#define AT91_SHDW_WKUPDBC_MASK GENMASK(31, 16)
#define AT91_SHDW_WKUPDBC(x) (((x) << AT91_SHDW_WKUPDBC_SHIFT) \
& AT91_SHDW_WKUPDBC_MASK)
#define AT91_SHDW_SR 0x08 /* Shut Down Status Register */
#define AT91_SHDW_WKUPIS_SHIFT 16
#define AT91_SHDW_WKUPIS_MASK GENMASK(31, 16)
#define AT91_SHDW_WKUPIS(x) ((1 << (x)) << AT91_SHDW_WKUPIS_SHIFT \
& AT91_SHDW_WKUPIS_MASK)
#define AT91_SHDW_WUIR 0x0c /* Shutdown Wake-up Inputs Register */
#define AT91_SHDW_WKUPEN_MASK GENMASK(15, 0)
#define AT91_SHDW_WKUPEN(x) ((1 << (x)) & AT91_SHDW_WKUPEN_MASK)
#define AT91_SHDW_WKUPT_SHIFT 16
#define AT91_SHDW_WKUPT_MASK GENMASK(31, 16)
#define AT91_SHDW_WKUPT(x) ((1 << (x)) << AT91_SHDW_WKUPT_SHIFT \
& AT91_SHDW_WKUPT_MASK)
#define SHDW_WK_PIN(reg, cfg) ((reg) & AT91_SHDW_WKUPIS((cfg)->wkup_pin_input))
#define SHDW_RTCWK(reg, cfg) (((reg) >> ((cfg)->sr_rtcwk_shift)) & 0x1)
#define SHDW_RTCWKEN(cfg) (1 << ((cfg)->mr_rtcwk_shift))
#define DBC_PERIOD_US(x) DIV_ROUND_UP_ULL((1000000 * (x)), \
SLOW_CLOCK_FREQ)
struct shdwc_config {
u8 wkup_pin_input;
u8 mr_rtcwk_shift;
u8 sr_rtcwk_shift;
};
struct shdwc {
struct shdwc_config *cfg;
void __iomem *at91_shdwc_base;
};
/*
* Hold configuration here, cannot be more than one instance of the driver
* since pm_power_off itself is global.
*/
static struct shdwc *at91_shdwc;
static struct clk *sclk;
static const unsigned long long sdwc_dbc_period[] = {
0, 3, 32, 512, 4096, 32768,
};
static void __init at91_wakeup_status(struct platform_device *pdev)
{
struct shdwc *shdw = platform_get_drvdata(pdev);
u32 reg;
char *reason = "unknown";
reg = readl(shdw->at91_shdwc_base + AT91_SHDW_SR);
dev_dbg(&pdev->dev, "%s: status = %#x\n", __func__, reg);
/* Simple power-on, just bail out */
if (!reg)
return;
if (SHDW_WK_PIN(reg, shdw->cfg))
reason = "WKUP pin";
else if (SHDW_RTCWK(reg, shdw->cfg))
reason = "RTC";
pr_info("AT91: Wake-Up source: %s\n", reason);
}
static void at91_poweroff(void)
{
writel(AT91_SHDW_KEY | AT91_SHDW_SHDW,
at91_shdwc->at91_shdwc_base + AT91_SHDW_CR);
}
static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
u32 in_period_us)
{
int i;
int max_idx = ARRAY_SIZE(sdwc_dbc_period) - 1;
unsigned long long period_us;
unsigned long long max_period_us = DBC_PERIOD_US(sdwc_dbc_period[max_idx]);
if (in_period_us > max_period_us) {
dev_warn(&pdev->dev,
"debouncer period %u too big, reduced to %llu us\n",
in_period_us, max_period_us);
return max_idx;
}
for (i = max_idx - 1; i > 0; i--) {
period_us = DBC_PERIOD_US(sdwc_dbc_period[i]);
dev_dbg(&pdev->dev, "%s: ref[%d] = %llu\n",
__func__, i, period_us);
if (in_period_us > period_us)
break;
}
return i + 1;
}
static u32 at91_shdwc_get_wakeup_input(struct platform_device *pdev,
struct device_node *np)
{
struct device_node *cnp;
u32 wk_input_mask;
u32 wuir = 0;
u32 wk_input;
for_each_child_of_node(np, cnp) {
if (of_property_read_u32(cnp, "reg", &wk_input)) {
dev_warn(&pdev->dev, "reg property is missing for %s\n",
cnp->full_name);
continue;
}
wk_input_mask = 1 << wk_input;
if (!(wk_input_mask & AT91_SHDW_WKUPEN_MASK)) {
dev_warn(&pdev->dev,
"wake-up input %d out of bounds ignore\n",
wk_input);
continue;
}
wuir |= wk_input_mask;
if (of_property_read_bool(cnp, "atmel,wakeup-active-high"))
wuir |= AT91_SHDW_WKUPT(wk_input);
dev_dbg(&pdev->dev, "%s: (child %d) wuir = %#x\n",
__func__, wk_input, wuir);
}
return wuir;
}
static void at91_shdwc_dt_configure(struct platform_device *pdev)
{
struct shdwc *shdw = platform_get_drvdata(pdev);
struct device_node *np = pdev->dev.of_node;
u32 mode = 0, tmp, input;
if (!np) {
dev_err(&pdev->dev, "device node not found\n");
return;
}
if (!of_property_read_u32(np, "debounce-delay-us", &tmp))
mode |= AT91_SHDW_WKUPDBC(at91_shdwc_debouncer_value(pdev, tmp));
if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
mode |= SHDW_RTCWKEN(shdw->cfg);
dev_dbg(&pdev->dev, "%s: mode = %#x\n", __func__, mode);
writel(mode, shdw->at91_shdwc_base + AT91_SHDW_MR);
input = at91_shdwc_get_wakeup_input(pdev, np);
writel(input, shdw->at91_shdwc_base + AT91_SHDW_WUIR);
}
static const struct shdwc_config sama5d2_shdwc_config = {
.wkup_pin_input = 0,
.mr_rtcwk_shift = 17,
.sr_rtcwk_shift = 5,
};
static const struct of_device_id at91_shdwc_of_match[] = {
{
.compatible = "atmel,sama5d2-shdwc",
.data = &sama5d2_shdwc_config,
}, {
/*sentinel*/
}
};
MODULE_DEVICE_TABLE(of, at91_shdwc_of_match);
static int __init at91_shdwc_probe(struct platform_device *pdev)
{
struct resource *res;
const struct of_device_id *match;
int ret;
if (!pdev->dev.of_node)
return -ENODEV;
at91_shdwc = devm_kzalloc(&pdev->dev, sizeof(*at91_shdwc), GFP_KERNEL);
if (!at91_shdwc)
return -ENOMEM;
platform_set_drvdata(pdev, at91_shdwc);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
at91_shdwc->at91_shdwc_base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(at91_shdwc->at91_shdwc_base)) {
dev_err(&pdev->dev, "Could not map reset controller address\n");
return PTR_ERR(at91_shdwc->at91_shdwc_base);
}
match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
at91_shdwc->cfg = (struct shdwc_config *)(match->data);
sclk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(sclk))
return PTR_ERR(sclk);
ret = clk_prepare_enable(sclk);
if (ret) {
dev_err(&pdev->dev, "Could not enable slow clock\n");
return ret;
}
at91_wakeup_status(pdev);
at91_shdwc_dt_configure(pdev);
pm_power_off = at91_poweroff;
return 0;
}
static int __exit at91_shdwc_remove(struct platform_device *pdev)
{
struct shdwc *shdw = platform_get_drvdata(pdev);
if (pm_power_off == at91_poweroff)
pm_power_off = NULL;
/* Reset values to disable wake-up features */
writel(0, shdw->at91_shdwc_base + AT91_SHDW_MR);
writel(0, shdw->at91_shdwc_base + AT91_SHDW_WUIR);
clk_disable_unprepare(sclk);
return 0;
}
static struct platform_driver at91_shdwc_driver = {
.remove = __exit_p(at91_shdwc_remove),
.driver = {
.name = "at91-shdwc",
.of_match_table = at91_shdwc_of_match,
},
};
module_platform_driver_probe(at91_shdwc_driver, at91_shdwc_probe);
MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
MODULE_DESCRIPTION("Atmel shutdown controller driver");
MODULE_LICENSE("GPL v2");