[PATCH v5 2/2] power: reset: at91-shdwc: add new shutdown controller driver

Nicolas Ferre
2016-03-16T13:19:50Z

Sama5d2 SoC has a completely new shutdown controller with new features and
register layout. It thus makes sense to add a new driver for this new
peripheral.

This driver is Device Tree only and handles events from the wake-up pin and
the RTC.
As the register layout may change in the future, so some values are encoded
in a configuration structure.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
---

Changes in v5:
- Instead of the "alternate shdwc" we choose a more specific
"sama5d2-compatible shdwc" wording. Change file name, in Kconfig, and the
MAINTAINERS file:
at91-shdwc.c -> at91-sama5d2_shdwc.c
"ATMEL AT91 Alternative Shutdown Controller" -> "ATMEL AT91 SAMA5D2-Compatible
Shutdown Controller"
- fix one indentation mismatch

Changes in v4:
- fix warning found by 0-day robot: large integer implicitly truncated to
unsigned type [-Woverflow]
- move to the property debounce-delay-us
- move to atmel,wakeup-active-high boolean
- add entry in MAINTAINERS file

Changes in v3:
- add the slow clock handle as the IP uses it
- remove useless protection at the beginning of pm_power_off handler
- allow to compile it as a module
- add COMPILE_TEST directive in Kconfig
- update description in file header

Changes in v2:
- add MODULE_DEVICE_TABLE as advised by Sebastian Reichel
- review indentation and braces to correct errors pointed out by checkpatch

MAINTAINERS | 5 +
drivers/power/reset/Kconfig | 8 +
drivers/power/reset/Makefile | 1 +
drivers/power/reset/at91-sama5d2_shdwc.c | 282 +++++++++++++++++++++++++++++++
4 files changed, 296 insertions(+)
create mode 100644 drivers/power/reset/at91-sama5d2_shdwc.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5744af3d79ab..a05b14d8d4d2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1999,6 +1999,11 @@ M: Nicolas Ferre <nicolas.ferre@atmel.com>
S: Supported
F: drivers/tty/serial/atmel_serial.c

+ATMEL AT91 SAMA5D2-Compatible Shutdown Controller
+M: Nicolas Ferre <nicolas.ferre@atmel.com>
+S: Supported
+F: drivers/power/reset/at91-sama5d2_shdwc.c
+
ATMEL SAMA5D2 ADC DRIVER
M: Ludovic Desroches <ludovic.desroches@atmel.com>
L: linux-iio at vger.kernel.org
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 0a6408a39c66..9bb2622c23bf 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -30,6 +30,14 @@ config POWER_RESET_AT91_RESET
This driver supports restart for Atmel AT91SAM9 and SAMA5
SoCs

+config POWER_RESET_AT91_SAMA5D2_SHDWC
+ tristate "Atmel AT91 SAMA5D2-Compatible shutdown controller driver"
+ depends on ARCH_AT91 || COMPILE_TEST
+ default SOC_SAMA5
+ help
+ This driver supports the alternate shutdown controller for some Atmel
+ SAMA5 SoCs. It is present for example on SAMA5D2 SoC.
+
config POWER_RESET_AXXIA
bool "LSI Axxia reset driver"
depends on ARCH_AXXIA
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 096fa67047f6..ab7aa8614d1f 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -1,6 +1,7 @@
obj-$(CONFIG_POWER_RESET_AS3722) += as3722-poweroff.o
obj-$(CONFIG_POWER_RESET_AT91_POWEROFF) += at91-poweroff.o
obj-$(CONFIG_POWER_RESET_AT91_RESET) += at91-reset.o
+obj-$(CONFIG_POWER_RESET_AT91_SAMA5D2_SHDWC) += at91-sama5d2_shdwc.o
obj-$(CONFIG_POWER_RESET_AXXIA) += axxia-reset.o
obj-$(CONFIG_POWER_RESET_BRCMSTB) += brcmstb-reboot.o
obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
diff --git a/drivers/power/reset/at91-sama5d2_shdwc.c b/drivers/power/reset/at91-sama5d2_shdwc.c
new file mode 100644
index 000000000000..8a5ac9706c9c
--- /dev/null
+++ b/drivers/power/reset/at91-sama5d2_shdwc.c
@@ -0,0 +1,282 @@
+/*
+ * 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");
--
2.1.3