linux-kernel - [PATCH 3/3] clocksource: fttmr010: refactor to handle clock

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Message-Id: <20170324213235.16119-3-linus.walleij@linaro.org>
Date:   Fri, 24 Mar 2017 22:32:35 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH 3/3] clocksource: fttmr010: refactor to handle clock

The plain Faraday FTTMR010 timer needs a clock to figure out its
tick rate, and the gemini reads it directly from the system
controller set-up. Split the init function and add two paths for
the two compatible-strings. We only support clocking using PCLK
because of lack of documentation on how EXTCLK works.

The Gemini still works like before, but we can also support a
generic, clock-based version.

Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
 drivers/clocksource/timer-fttmr010.c | 119 +++++++++++++++++++++--------------
 1 file changed, 73 insertions(+), 46 deletions(-)

diff --git a/drivers/clocksource/timer-fttmr010.c b/drivers/clocksource/timer-fttmr010.c
index e37ec3d69a7e..b4a6f1e4bc54 100644
--- a/drivers/clocksource/timer-fttmr010.c
+++ b/drivers/clocksource/timer-fttmr010.c
@@ -16,17 +16,7 @@
 #include <linux/clockchips.h>
 #include <linux/clocksource.h>
 #include <linux/sched_clock.h>
-
-/*
- * Relevant registers in the global syscon
- */
-#define GLOBAL_STATUS		0x04
-#define CPU_AHB_RATIO_MASK	(0x3 << 18)
-#define CPU_AHB_1_1		(0x0 << 18)
-#define CPU_AHB_3_2		(0x1 << 18)
-#define CPU_AHB_24_13		(0x2 << 18)
-#define CPU_AHB_2_1		(0x3 << 18)
-#define REG_TO_AHB_SPEED(reg)	((((reg) >> 15) & 0x7) * 10 + 130)
+#include <linux/clk.h>
 
 /*
  * Register definitions for the timers
@@ -189,23 +179,9 @@ static struct irqaction fttmr010_timer_irq = {
 	.handler	= fttmr010_timer_interrupt,
 };
 
-static int __init gemini_timer_of_init(struct device_node *np)
+static int __init fttmr010_timer_common_init(struct device_node *np)
 {
-	static struct regmap *map;
 	int irq;
-	int ret;
-	u32 val;
-
-	map = syscon_regmap_lookup_by_phandle(np, "syscon");
-	if (IS_ERR(map)) {
-		pr_err("Can't get regmap for syscon handle");
-		return -ENODEV;
-	}
-	ret = regmap_read(map, GLOBAL_STATUS, &val);
-	if (ret) {
-		pr_err("Can't read syscon status register");
-		return -ENXIO;
-	}
 
 	base = of_iomap(np, 0);
 	if (!base) {
@@ -219,26 +195,6 @@ static int __init gemini_timer_of_init(struct device_node *np)
 		return -EINVAL;
 	}
 
-	tick_rate = REG_TO_AHB_SPEED(val) * 1000000;
-	printk(KERN_INFO "Bus: %dMHz", tick_rate / 1000000);
-
-	tick_rate /= 6;		/* APB bus run AHB*(1/6) */
-
-	switch (val & CPU_AHB_RATIO_MASK) {
-	case CPU_AHB_1_1:
-		printk(KERN_CONT "(1/1)\n");
-		break;
-	case CPU_AHB_3_2:
-		printk(KERN_CONT "(3/2)\n");
-		break;
-	case CPU_AHB_24_13:
-		printk(KERN_CONT "(24/13)\n");
-		break;
-	case CPU_AHB_2_1:
-		printk(KERN_CONT "(2/1)\n");
-		break;
-	}
-
 	/*
 	 * Reset the interrupt mask and status
 	 */
@@ -273,4 +229,75 @@ static int __init gemini_timer_of_init(struct device_node *np)
 
 	return 0;
 }
+
+static int __init fttmr010_timer_of_init(struct device_node *np)
+{
+	/*
+	 * These implementations require a clock reference.
+	 * FIXME: we currently only support clocking using PCLK
+	 * and using EXTCLK is not supported in the driver.
+	 */
+	struct clk *clk;
+
+	clk = of_clk_get_by_name(np, "PCLK");
+	if (IS_ERR(clk)) {
+		pr_err("could not get PCLK");
+		return PTR_ERR(clk);
+	}
+	tick_rate = clk_get_rate(clk);
+
+	return fttmr010_timer_common_init(np);
+}
+CLOCKSOURCE_OF_DECLARE(fttmr010, "faraday,fttmr010", fttmr010_timer_of_init);
+
+/*
+ * Gemini-specific: relevant registers in the global syscon
+ */
+#define GLOBAL_STATUS		0x04
+#define CPU_AHB_RATIO_MASK	(0x3 << 18)
+#define CPU_AHB_1_1		(0x0 << 18)
+#define CPU_AHB_3_2		(0x1 << 18)
+#define CPU_AHB_24_13		(0x2 << 18)
+#define CPU_AHB_2_1		(0x3 << 18)
+#define REG_TO_AHB_SPEED(reg)	((((reg) >> 15) & 0x7) * 10 + 130)
+
+static int __init gemini_timer_of_init(struct device_node *np)
+{
+	static struct regmap *map;
+	int ret;
+	u32 val;
+
+	map = syscon_regmap_lookup_by_phandle(np, "syscon");
+	if (IS_ERR(map)) {
+		pr_err("Can't get regmap for syscon handle\n");
+		return -ENODEV;
+	}
+	ret = regmap_read(map, GLOBAL_STATUS, &val);
+	if (ret) {
+		pr_err("Can't read syscon status register\n");
+		return -ENXIO;
+	}
+
+	tick_rate = REG_TO_AHB_SPEED(val) * 1000000;
+	pr_info("Bus: %dMHz ", tick_rate / 1000000);
+
+	tick_rate /= 6;		/* APB bus run AHB*(1/6) */
+
+	switch (val & CPU_AHB_RATIO_MASK) {
+	case CPU_AHB_1_1:
+		pr_cont("(1/1)\n");
+		break;
+	case CPU_AHB_3_2:
+		pr_cont("(3/2)\n");
+		break;
+	case CPU_AHB_24_13:
+		pr_cont("(24/13)\n");
+		break;
+	case CPU_AHB_2_1:
+		pr_cont("(2/1)\n");
+		break;
+	}
+
+	return fttmr010_timer_common_init(np);
+}
 CLOCKSOURCE_OF_DECLARE(gemini, "cortina,gemini-timer", gemini_timer_of_init);
-- 
2.9.3