[PATCH v2] watchdog: ebc-c384_wdt: Migrate to the regmap API

[William Breathitt Gray <william.gray@linaro.org>]

The regmap API supports IO port accessors so we can take advantage of
regmap abstractions rather than handling access to the device registers
directly in the driver.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
Changes in v2:
 - Utilize watchdog_set_drvdata() and watchdog_get_drvdata()
 - Map watchdog control registers based on offset 0x1 and adjust regmap
   configurations accordingly; offset 0x0 is unused in this driver so we
   should avoid unnecessary exposure of it

 drivers/watchdog/Kconfig        |  1 +
 drivers/watchdog/ebc-c384_wdt.c | 67 +++++++++++++++++++++++----------
 2 files changed, 49 insertions(+), 19 deletions(-)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index f0872970daf9..301cfe79263c 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1089,6 +1089,7 @@ config EBC_C384_WDT
 	tristate "WinSystems EBC-C384 Watchdog Timer"
 	depends on X86
 	select ISA_BUS_API
+	select REGMAP_MMIO
 	select WATCHDOG_CORE
 	help
 	  Enables watchdog timer support for the watchdog timer on the
diff --git a/drivers/watchdog/ebc-c384_wdt.c b/drivers/watchdog/ebc-c384_wdt.c
index 8ef4b0df3855..2f9fec5073b3 100644
--- a/drivers/watchdog/ebc-c384_wdt.c
+++ b/drivers/watchdog/ebc-c384_wdt.c
@@ -3,15 +3,15 @@
  * Watchdog timer driver for the WinSystems EBC-C384
  * Copyright (C) 2016 William Breathitt Gray
  */
+#include <linux/bits.h>
 #include <linux/device.h>
 #include <linux/dmi.h>
-#include <linux/errno.h>
-#include <linux/io.h>
-#include <linux/ioport.h>
+#include <linux/err.h>
 #include <linux/isa.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/regmap.h>
 #include <linux/types.h>
 #include <linux/watchdog.h>
 
@@ -24,8 +24,14 @@
 #define WATCHDOG_MAX_TIMEOUT	15300
 #define BASE_ADDR		0x564
 #define ADDR_EXTENT		5
-#define CFG_ADDR		(BASE_ADDR + 1)
-#define PET_ADDR		(BASE_ADDR + 2)
+#define CTRL_BASE_ADDR		(BASE_ADDR + 0x1)
+#define CTRL_ADDR_EXTENT	2
+#define CTRL_MAX_REGISTER	(CTRL_ADDR_EXTENT - 1)
+#define CFG_REG			0x0
+#define PET_REG			0x1
+#define CFG_MINUTES		0x00
+#define CFG_SECONDS		BIT(7)
+#define PET_DISABLED		0x00
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
@@ -37,43 +43,54 @@ module_param(timeout, uint, 0);
 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
 	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 
+static const struct regmap_range ebc_c384_wdt_wr_ranges[] = {
+	regmap_reg_range(0x0, 0x1),
+};
+static const struct regmap_access_table ebc_c384_wdt_wr_table = {
+	.yes_ranges = ebc_c384_wdt_wr_ranges,
+	.n_yes_ranges = ARRAY_SIZE(ebc_c384_wdt_wr_ranges),
+};
+static const struct regmap_config ebc_c384_wdt_regmap_config = {
+	.reg_bits = 8,
+	.reg_stride = 1,
+	.val_bits = 8,
+	.io_port = true,
+	.max_register = CTRL_MAX_REGISTER,
+	.wr_table = &ebc_c384_wdt_wr_table,
+};
+
 static int ebc_c384_wdt_start(struct watchdog_device *wdev)
 {
+	struct regmap *const map = watchdog_get_drvdata(wdev);
 	unsigned t = wdev->timeout;
 
 	/* resolution is in minutes for timeouts greater than 255 seconds */
 	if (t > 255)
 		t = DIV_ROUND_UP(t, 60);
 
-	outb(t, PET_ADDR);
-
-	return 0;
+	return regmap_write(map, PET_REG, t);
 }
 
 static int ebc_c384_wdt_stop(struct watchdog_device *wdev)
 {
-	outb(0x00, PET_ADDR);
+	struct regmap *const map = watchdog_get_drvdata(wdev);
 
-	return 0;
+	return regmap_write(map, PET_REG, PET_DISABLED);
 }
 
 static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t)
 {
+	struct regmap *const map = watchdog_get_drvdata(wdev);
+
 	/* resolution is in minutes for timeouts greater than 255 seconds */
 	if (t > 255) {
 		/* round second resolution up to minute granularity */
 		wdev->timeout = roundup(t, 60);
-
-		/* set watchdog timer for minutes */
-		outb(0x00, CFG_ADDR);
-	} else {
-		wdev->timeout = t;
-
-		/* set watchdog timer for seconds */
-		outb(0x80, CFG_ADDR);
+		return regmap_write(map, CFG_REG, CFG_MINUTES);
 	}
 
-	return 0;
+	wdev->timeout = t;
+	return regmap_write(map, CFG_REG, CFG_SECONDS);
 }
 
 static const struct watchdog_ops ebc_c384_wdt_ops = {
@@ -89,6 +106,8 @@ static const struct watchdog_info ebc_c384_wdt_info = {
 
 static int ebc_c384_wdt_probe(struct device *dev, unsigned int id)
 {
+	void __iomem *regs;
+	struct regmap *map;
 	struct watchdog_device *wdd;
 
 	if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) {
@@ -97,6 +116,15 @@ static int ebc_c384_wdt_probe(struct device *dev, unsigned int id)
 		return -EBUSY;
 	}
 
+	regs = devm_ioport_map(dev, CTRL_BASE_ADDR, CTRL_ADDR_EXTENT);
+	if (!regs)
+		return -ENOMEM;
+
+	map = devm_regmap_init_mmio(dev, regs, &ebc_c384_wdt_regmap_config);
+	if (IS_ERR(map))
+		return dev_err_probe(dev, PTR_ERR(map),
+				     "Unable to initialize register map\n");
+
 	wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
 	if (!wdd)
 		return -ENOMEM;
@@ -107,6 +135,7 @@ static int ebc_c384_wdt_probe(struct device *dev, unsigned int id)
 	wdd->min_timeout = 1;
 	wdd->max_timeout = WATCHDOG_MAX_TIMEOUT;
 
+	watchdog_set_drvdata(wdd, map);
 	watchdog_set_nowayout(wdd, nowayout);
 	watchdog_init_timeout(wdd, timeout, dev);
 

base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
-- 
2.39.2