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From:   David Ober <dober6023@gmail.com>
To:     linux-hwmon@vger.kernel.org
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        jdelvare@suse.com, linux@roeck-us.net, corbet@lwn.net,
        dober@lenovo.com, mpearson@lenovo.com,
        David Ober <dober6023@gmail.com>
Subject: [PATCH v2] New module to add NCT6692D watchdog funtionality
Date:   Tue, 13 Jun 2023 09:33:34 -0400
Message-Id: <20230613133334.64306-1-dober6023@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The new module adds in the basic functionality of the NCT6692D
watchdog driver. This functionality is added to support the
Lenovo SE30 device

Signed-off-by: David Ober <dober6023@gmail.com>

V2 removed report functions as they are not used
V2 combined repeated code into function as suggested
V2 Formating and syntax changes needed by reviewer and --strict option
---
 drivers/watchdog/Kconfig       |  10 +
 drivers/watchdog/Makefile      |   1 +
 drivers/watchdog/nct6692_wdt.c | 535 +++++++++++++++++++++++++++++++++
 3 files changed, 546 insertions(+)
 create mode 100644 drivers/watchdog/nct6692_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index f22138709bf5..75008ef87ce3 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1672,6 +1672,16 @@ config SIEMENS_SIMATIC_IPC_WDT
 	  To compile this driver as a module, choose M here: the module will be
 	  called simatic-ipc-wdt.
 
+config NCT6692_WDT
+        tristate "Nuvoton NCT6692D Watchdog"
+        select WATCHDOG_CORE
+        help
+          If you say yes here you get support for the hardware watchdog
+          functionality of the Nuvoton NCT6692D eSIO chip.
+
+          This driver can also be built as a module. If so, the module
+          will be called nct6692_wdt.
+
 # M68K Architecture
 
 config M54xx_WATCHDOG
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index b4c4ccf2d703..2ec1e703faae 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -151,6 +151,7 @@ obj-$(CONFIG_NIC7018_WDT) += nic7018_wdt.o
 obj-$(CONFIG_MLX_WDT) += mlx_wdt.o
 obj-$(CONFIG_KEEMBAY_WATCHDOG) += keembay_wdt.o
 obj-$(CONFIG_SIEMENS_SIMATIC_IPC_WDT) += simatic-ipc-wdt.o
+obj-$(CONFIG_NCT6692D_WDT) += nct6692_wdt.o
 
 # M68K Architecture
 obj-$(CONFIG_M54xx_WATCHDOG) += m54xx_wdt.o
diff --git a/drivers/watchdog/nct6692_wdt.c b/drivers/watchdog/nct6692_wdt.c
new file mode 100644
index 000000000000..745d200e8bcc
--- /dev/null
+++ b/drivers/watchdog/nct6692_wdt.c
@@ -0,0 +1,535 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NCT6692D Watchdog Driver
+ */
+
+#define dev_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/iommu.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+/* ISA constants */
+
+#define IOREGION_OFFSET		4       /* Use EC port 1 */
+#define IOREGION_LENGTH		4
+
+#define WATCHDOG_TIMEOUT	60 /* 60 sec default timeout */
+
+/*The timeout range is 1-255 seconds*/
+#define MIN_TIMEOUT		1
+#define MAX_TIMEOUT		255
+
+static int timeout; /* in seconds */
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout,
+		 "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
+		 __MODULE_STRING(WATCHDOG_TIMEOUT) ".");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+		 "Watchdog cannot be stopped once started (default="
+		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#define WDT_EFER(X) (X)  /* Extended Function Enable Registers */
+#define WDT_EFIR(X) (X)  /* Extended Function Index Register(same as EFER) */
+#define WDT_EFDR(X) (WDT_EFIR(X) + 1) /* Extended Function Data Register */
+
+#define DRVNAME				"nct6692"
+#define NCT6692_ID			0x0110
+#define CHIPID_MASK			0xFFF0
+
+#define NCT6692_MAX_IO_RETRY_NUM	0x100
+
+#define NCT6692_EC_NAME			"nct6692_ec"
+#define NCT6692_HWM_CFG			0x180
+
+#define NCT6692_SIO_UNLOCK_KEY		0x87
+#define NCT6692_SIO_LOCK_KEY		0xAA
+#define NCT6692_LD_NUM_SHM		0x0F
+#define NCT6692_LD_WIN2_BASE_ADDR	0xF8
+
+/* Host Interface WIN2 offset definition */
+#define SHM_WIN_MOD_OFFSET		0x01
+#define SHM_WIN_CMD_OFFSET		0x02
+#define SHM_WIN_SEL_OFFSET		0x03
+#define SHM_WIN_CTL_OFFSET		0x04
+#define VAL_SHM_WIN_CTRL_WR		0x40
+#define VAL_SHM_WIN_CTRL_RD		0x80
+#define SHM_WIN_ID_OFFSET		0x08
+#define SHM_WIN_DAT_OFFSET		0x10
+
+struct nct6692_shm_t {
+	u_char __iomem *base_addr;
+	u_long base_phys;
+	u_char offset_mod;
+	u_char offset_cmd;
+	u_char offset_sel;
+	u_char offset_ctl;
+	u_char offset_id;
+	u_char offset_dat;
+};
+
+/* REGs definitions */
+enum nct6692_channel_type {
+	NCT6692_CHANNEL_DEFAULT,
+};
+
+struct nct6692_sio_data {
+	u_long base_phys;
+	int sioreg;
+};
+
+struct nct6692_reg_t {
+	u_char channel;  /* nct6692_channel_type */
+	u_char mod;
+	u_char cmd;
+	u_char sel;
+	u_int idx;
+};
+
+struct nct6692_data_t {
+	struct nct6692_shm_t shm;
+	struct nct6692_reg_t cfg;
+	struct nct6692_reg_t cnt;
+	struct watchdog_device wdt;
+};
+
+static inline void superio_outb(int ioreg, int reg, int val)
+{
+	outb(reg, WDT_EFER(ioreg));
+	outb(val, WDT_EFDR(ioreg));
+}
+
+static inline int superio_inb(int ioreg, int reg)
+{
+	outb(reg, WDT_EFER(ioreg));
+	return inb(WDT_EFDR(ioreg));
+}
+
+static inline int superio_enter(int key, int addr, const char *name)
+{
+	if (!request_muxed_region(addr, 2, name)) {
+		pr_err("I/O address 0x%04x already in use\n", addr);
+		return -EBUSY;
+	}
+	outb_p(key, WDT_EFER(addr)); /* Enter extended function mode */
+	outb_p(key, WDT_EFER(addr)); /* Again according to manual */
+
+	return 0;
+}
+
+static inline void superio_select(int ioreg, int ld)
+{
+	superio_outb(ioreg, 0x07, ld);
+}
+
+static inline void superio_exit(int key, int addr)
+{
+	outb_p(key, WDT_EFER(addr)); /* Leave extended function mode */
+	release_region(addr, 2);
+}
+
+/*
+ * The following several functions are used to access host interface according
+ * to the definition of memory region, reg (as a base addr) and an index offset
+ * It uses (shm.base_addr + shm.offset) format to locate the data area of the
+ * host interface channel. Then access the address "reg.idx + idx_offset" that
+ * are suitable for a loop accessing. Where the idx_offset is an extra offset
+ * based on the definition of reg for accessing the address based on the reg.
+ */
+
+static u_char shm_get_new_id(const struct nct6692_shm_t *shm,
+			     u_char pre_id)
+{
+	u_char new_id;
+	u_int count = 0;
+
+	do {
+		msleep(20);
+		new_id = ioread8(shm->base_addr + shm->offset_id);
+		if (count == NCT6692_MAX_IO_RETRY_NUM)
+			return new_id;
+		count++;
+	} while (pre_id == new_id);
+
+	return new_id;
+}
+
+static int read_shm_win(const struct nct6692_shm_t *shm,
+			const struct nct6692_reg_t *reg,
+			u_char idx_offset)
+{
+	u_char pre_id;
+	int retval;
+
+	if (!request_mem_region(shm->base_phys, 256, NCT6692_EC_NAME)) {
+		pr_err("nuv:request I/O channel busy (base_addr=%lX)\n",
+		       shm->base_phys);
+		return -EBUSY;
+	}
+
+	iowrite8(reg->mod, shm->base_addr + shm->offset_mod);
+	iowrite8(reg->cmd, shm->base_addr + shm->offset_cmd);
+	iowrite8(reg->sel, shm->base_addr + shm->offset_sel);
+	pre_id = ioread8(shm->base_addr + shm->offset_id);
+	iowrite8(VAL_SHM_WIN_CTRL_RD, shm->base_addr + shm->offset_ctl);
+	if (shm_get_new_id(shm, pre_id) == pre_id) {
+		pr_warn("nuv:Wait ID timeout in %s!\n", __func__);
+		retval = -EINVAL;
+		goto exit_release;
+	}
+	retval = ioread8(shm->base_addr + shm->offset_dat + reg->idx + idx_offset);
+
+exit_release:
+	release_mem_region(shm->base_phys, 256);
+	return retval;
+}
+
+static int write_shm_win(const struct nct6692_shm_t *shm,
+			 const struct nct6692_reg_t *reg,
+			 u_char idx_offset,
+			 u_char val)
+{
+	int err = 0;
+	u_char pre_id;
+	u_char new_id;
+
+	if (!request_mem_region(shm->base_phys, 256, NCT6692_EC_NAME)) {
+		pr_err("nuv:request I/O channel busy (base_addr=%lX)\n",
+		       shm->base_phys);
+		return -EBUSY;
+	}
+
+	iowrite8(reg->mod, shm->base_addr + shm->offset_mod);
+	iowrite8(reg->cmd, shm->base_addr + shm->offset_cmd);
+	iowrite8(reg->sel, shm->base_addr + shm->offset_sel);
+
+	pre_id = ioread8(shm->base_addr + shm->offset_id);
+	iowrite8(VAL_SHM_WIN_CTRL_RD, shm->base_addr + shm->offset_ctl);
+	new_id = shm_get_new_id(shm, pre_id);
+	if (new_id == pre_id) {
+		pr_warn("nuv:Wait ID Read timeout in %s!\n", __func__);
+		err = -EINVAL;
+		goto err_exit_release;
+	}
+
+	iowrite8(val, shm->base_addr + shm->offset_dat + reg->idx + idx_offset);
+
+	pre_id = new_id;
+
+	iowrite8(VAL_SHM_WIN_CTRL_WR, shm->base_addr + shm->offset_ctl);
+	if (shm_get_new_id(shm, pre_id) == pre_id) {
+		pr_warn("nuv:Wait ID Write timeout in %s!\n", __func__);
+		err = -EINVAL;
+	}
+
+err_exit_release:
+	release_mem_region(shm->base_phys, 256);
+	return err;
+}
+
+static int nct6692_wdt_enable(bool enable, u_int timeout,
+			      struct nct6692_data_t *data)
+{
+	u_char reg;
+
+	reg = read_shm_win(&data->shm, &data->cfg, 0);
+
+	if (enable) {
+		write_shm_win(&data->shm, &data->cfg, 0, 0x02);
+		/* ^^^^ 0x00 to disable reboot */
+		write_shm_win(&data->shm, &data->cnt, 0, timeout);
+		reg = read_shm_win(&data->shm, &data->cfg, 0);
+	} else {
+		write_shm_win(&data->shm, &data->cnt, 0, timeout);
+	}
+	reg = read_shm_win(&data->shm, &data->cfg, 0);
+	reg = read_shm_win(&data->shm, &data->cnt, 0);
+	return 0;
+}
+
+static int nct6692_wdt_set_time(struct watchdog_device *wdog, u_int timeout)
+{
+	struct nct6692_data_t *data = watchdog_get_drvdata(wdog);
+
+	if (timeout != 0)
+		nct6692_wdt_enable(true, timeout, data);
+	else
+		nct6692_wdt_enable(false, timeout, data);
+
+	return 0;
+}
+
+static int nct6692_wdt_setup(struct watchdog_device *wdt)
+{
+	u_char timeout, cfg;
+	struct nct6692_data_t *data = watchdog_get_drvdata(wdt);
+
+	timeout = 0;
+
+	timeout = read_shm_win(&data->shm, &data->cnt, 0);
+	cfg = read_shm_win(&data->shm, &data->cfg, 0);
+	if (timeout) {
+		dev_err(data->wdt.parent, "failed to initialize watchdog (timeout=%d)\n", timeout);
+		return timeout;
+	}
+	return timeout;
+}
+
+static int nct6692_wdt_start(struct watchdog_device *wdog)
+{
+	nct6692_wdt_setup(wdog);
+	nct6692_wdt_set_time(wdog, wdog->timeout);
+	return 0;
+}
+
+static int nct6692_wdt_stop(struct watchdog_device *wdog)
+{
+	return nct6692_wdt_set_time(wdog, 0);
+}
+
+static int nct6692_wdt_set_timeout(struct watchdog_device *wdog,
+				   u_int timeout)
+{
+	wdog->timeout = timeout;
+	return 0;
+}
+
+static u_int nct6692_wdt_get_timeleft(struct watchdog_device *wdog)
+{
+	struct nct6692_data_t *data = watchdog_get_drvdata(wdog);
+	u_int timeleft;
+
+	timeleft = read_shm_win(&data->shm, &data->cnt, 0);
+	return timeleft;
+}
+
+static int nct6692_wdt_ping(struct watchdog_device *wdt)
+{
+	struct nct6692_data_t *data = watchdog_get_drvdata(wdt);
+	int timeout;
+
+	/*
+	 * Note:
+	 * NCT6692 does not support refreshing WDT_TIMER_REG register when
+	 * the watchdog is active. Please disable watchdog before feeding
+	 * the watchdog and enable it again.
+	 */
+	/* Disable soft watchdog timer */
+	timeout = 0;
+	nct6692_wdt_enable(false, timeout, data);
+
+	/* feed watchdog */
+	timeout = wdt->timeout;
+	write_shm_win(&data->shm, &data->cnt, 0, timeout);
+
+	/* Enable soft watchdog timer */
+	nct6692_wdt_enable(true, timeout, data);
+	return 0;
+}
+
+static const struct watchdog_info nct6692_wdt_info = {
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE,
+	.identity	= "nct6692 watchdog",
+};
+
+static const struct watchdog_ops nct6692_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= nct6692_wdt_start,
+	.stop		= nct6692_wdt_stop,
+	.ping		= nct6692_wdt_ping,
+	.set_timeout	= nct6692_wdt_set_timeout,
+	.get_timeleft	= nct6692_wdt_get_timeleft,
+};
+
+static int nct6692_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct nct6692_data_t *data = NULL;
+	struct nct6692_sio_data *sio_data = dev->platform_data;
+	struct resource *res;
+
+	dev_info(&pdev->dev, "Probe NCT6692 called\n");
+	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/* init value */
+	data->shm.base_phys = sio_data->base_phys;
+	data->shm.base_addr = ioremap_cache(data->shm.base_phys, 256);
+
+	data->shm.offset_mod = SHM_WIN_MOD_OFFSET;
+	data->shm.offset_cmd = SHM_WIN_CMD_OFFSET;
+	data->shm.offset_sel = SHM_WIN_SEL_OFFSET;
+	data->shm.offset_ctl = SHM_WIN_CTL_OFFSET;
+	data->shm.offset_id  = SHM_WIN_ID_OFFSET;
+	data->shm.offset_dat = SHM_WIN_DAT_OFFSET;
+
+	data->cfg.channel = NCT6692_CHANNEL_DEFAULT;
+	data->cfg.mod = 0x10;
+	data->cfg.idx = 0x15;
+	data->cnt.channel = NCT6692_CHANNEL_DEFAULT;
+	data->cnt.mod = 0x10;
+	data->cnt.idx = 0x16;
+
+	data->wdt.ops = &nct6692_wdt_ops;
+	data->wdt.info = &nct6692_wdt_info;
+
+	data->wdt.timeout = WATCHDOG_TIMEOUT; /* Set default timeout */
+	data->wdt.min_timeout = MIN_TIMEOUT;
+	data->wdt.max_timeout = MAX_TIMEOUT;
+	data->wdt.parent = &pdev->dev;
+
+	watchdog_init_timeout(&data->wdt, timeout, &pdev->dev);
+	watchdog_set_drvdata(&data->wdt, data);
+
+	watchdog_set_nowayout(&data->wdt, nowayout);
+	watchdog_stop_on_reboot(&data->wdt);
+	watchdog_stop_on_unregister(&data->wdt);
+
+	return devm_watchdog_register_device(dev, &data->wdt);
+}
+
+static struct platform_driver nct6692_driver = {
+	.driver = {
+		.name = DRVNAME,
+	},
+	.probe	= nct6692_probe,
+};
+
+static int __init nct6692_find(int addr, u_long *base_phys)
+{
+	u16 val;
+	int err = 0;
+	u_long tmp_base_phys;
+
+	err = superio_enter(NCT6692_SIO_UNLOCK_KEY, addr, DRVNAME);
+	if (err)
+		return err;
+
+	val = superio_inb(addr, 0x20);
+	val = ((val << 8) | (superio_inb(addr, 0x21))) & CHIPID_MASK;
+
+	if (val != NCT6692_ID) {
+		err = -ENODEV;
+		goto fail;
+	}
+
+	superio_select(addr, NCT6692_LD_NUM_SHM);
+	tmp_base_phys = (superio_inb(addr, NCT6692_LD_WIN2_BASE_ADDR) |
+			 (superio_inb(addr, NCT6692_LD_WIN2_BASE_ADDR + 1) << 8) |
+			 (superio_inb(addr, NCT6692_LD_WIN2_BASE_ADDR + 2) << 16) |
+			 (superio_inb(addr, NCT6692_LD_WIN2_BASE_ADDR + 3) << 24)) &
+			0xFFFFFFFF;
+
+	if (tmp_base_phys == 0xFFFFFFFF || tmp_base_phys == 0) {
+		err = -ENODEV;
+		goto fail;
+	}
+
+fail:
+	superio_exit(NCT6692_SIO_LOCK_KEY, addr);
+	if (!err) {
+		if (base_phys)
+			*base_phys = tmp_base_phys;
+	}
+	return err;
+}
+
+static struct platform_device *pdev;
+
+static int __init nct6692_init(void)
+{
+	struct nct6692_sio_data sio_data;
+	int sioaddr[2] = { 0x2e, 0x4e };
+	struct resource res;
+	int err;
+	int address;
+	u_long base_phys;
+
+	/*
+	 * initialize sio_data->kind and sio_data->sioreg.
+	 *
+	 * when Super-I/O functions move to a separate file, the Super-I/O
+	 * driver will probe 0x2e and 0x4e and auto-detect the presence of a
+	 * nct6692 hardware monitor, and call probe()
+	 */
+	err = nct6692_find(sioaddr[0], &base_phys);
+	if (err) {
+		err = nct6692_find(sioaddr[1], &base_phys);
+		if (err)
+			return -ENODEV;
+	}
+
+	memset(&res, 0, sizeof(res));
+	res.name = DRVNAME;
+	res.start = address + IOREGION_OFFSET;
+	res.end = address + IOREGION_OFFSET + IOREGION_LENGTH - 1;
+	res.flags = IORESOURCE_IO;
+
+	err = acpi_check_resource_conflict(&res);
+	if (err)
+		return err;
+
+	platform_driver_register(&nct6692_driver);
+
+	sio_data.base_phys = base_phys;
+
+	pdev = platform_device_alloc(DRVNAME, base_phys);
+	if (!pdev) {
+		err = -ENOMEM;
+		goto exit_device_unregister;
+	}
+	err = platform_device_add_data(pdev, &sio_data,
+				       sizeof(struct nct6692_sio_data));
+	if (err)
+		goto exit_device_put;
+
+	err = platform_device_add_resources(pdev, &res, 1);
+	if (err)
+		goto exit_device_put;
+
+	dev_info(&pdev->dev, "NCT6692 device found\n");
+	/* platform_device_add calls probe() */
+	err = platform_device_add(pdev);
+	if (err)
+		goto exit_device_put;
+
+	return 0;
+exit_device_put:
+	platform_device_put(pdev);
+exit_device_unregister:
+	if (pdev)
+		platform_device_unregister(pdev);
+	platform_driver_unregister(&nct6692_driver);
+	return err;
+}
+
+static void __exit nct6692_exit(void)
+{
+	platform_device_unregister(pdev);
+	platform_driver_unregister(&nct6692_driver);
+}
+
+MODULE_AUTHOR("David Ober <dober@lenovo.com>");
+MODULE_DESCRIPTION("NCT6692D driver");
+MODULE_LICENSE("GPL");
+
+module_init(nct6692_init);
+module_exit(nct6692_exit);
-- 
2.34.1