From: Ingo van Lil <inguin@gmx.de>
To: linux-kernel@vger.kernel.org
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>,
        Boris Brezillon <boris.brezillon@free-electrons.com>,
        Nicolas Ferre <nicolas.ferre@atmel.com>, linux-clk@vger.kernel.org,
        Ingo van Lil <inguin@gmx.de>
Subject: [PATCH] clk: at91: utmi: Support configurable multipliers
Date: Mon, 10 Jul 2017 14:24:09 +0200
Message-Id: <20170710122409.3017-1-inguin@gmx.de>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 5729
Lines: 196

The AT91 UTMI clock is a PLL generating the 480 MHz USB clock.
Originally, this PLL always had a fixed x40 multiplier, thus requiring
a 12 MHz input clock. Recent SOCs (sama5d2 and sama5d3) have a special
function register for configuring this multiplier, allowing to use
different main clock frequencies.

Signed-off-by: Ingo van Lil <inguin@gmx.de>
---
 drivers/clk/at91/clk-utmi.c  | 105 +++++++++++++++++++++++++++++++++++++++++--
 include/soc/at91/atmel-sfr.h |   2 +
 2 files changed, 104 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/at91/clk-utmi.c b/drivers/clk/at91/clk-utmi.c
index aadabd9..d41c38b 100644
--- a/drivers/clk/at91/clk-utmi.c
+++ b/drivers/clk/at91/clk-utmi.c
@@ -14,14 +14,29 @@
 #include <linux/of.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
+#include <soc/at91/atmel-sfr.h>
 
 #include "pmc.h"
 
+/* default multiplier for SOCs that do not allow configuration via SFR */
 #define UTMI_FIXED_MUL		40
 
+/* supported multiplier settings for SOCs that allow configuration via SFR */
+struct utmi_multipliers {
+	const char *sfr_compatible_name;
+	u8 multipliers[4];
+};
+
+static const struct utmi_multipliers utmi_multipliers[] = {
+	{ "atmel,sama5d2-sfr", { 40, 30, 20, 40 } },
+	{ "atmel,sama5d3-sfr", { 40, 30, 20, 10 } },
+};
+
 struct clk_utmi {
 	struct clk_hw hw;
 	struct regmap *regmap;
+	struct regmap *sfr_regmap;
+	const u8 *multipliers;
 };
 
 #define to_clk_utmi(hw) container_of(hw, struct clk_utmi, hw)
@@ -66,8 +81,67 @@ static void clk_utmi_unprepare(struct clk_hw *hw)
 static unsigned long clk_utmi_recalc_rate(struct clk_hw *hw,
 					  unsigned long parent_rate)
 {
-	/* UTMI clk is a fixed clk multiplier */
-	return parent_rate * UTMI_FIXED_MUL;
+	struct clk_utmi *utmi = to_clk_utmi(hw);
+	u8 mul = UTMI_FIXED_MUL;
+
+	if (utmi->sfr_regmap && utmi->multipliers) {
+		u32 regval;
+		regmap_read(utmi->sfr_regmap, AT91_SFR_UTMICKTRIM, &regval);
+		mul = utmi->multipliers[regval & AT91_UTMICKTRIM_FREQ_MASK];
+	}
+
+	return parent_rate * mul;
+}
+
+static long clk_utmi_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *parent_rate)
+{
+	struct clk_utmi *utmi = to_clk_utmi(hw);
+	unsigned long bestrate = 0;
+	int bestdiff = -1;
+	int i;
+
+	if (!utmi->sfr_regmap || !utmi->multipliers)
+		return *parent_rate * UTMI_FIXED_MUL;
+
+	for (i = 0; i < ARRAY_SIZE(utmi_multipliers); i++) {
+		unsigned long tmprate = *parent_rate * utmi->multipliers[i];
+		int tmpdiff;
+
+		if (tmprate < rate)
+			continue;
+
+		tmpdiff = tmprate - rate;
+		if (bestdiff < 0 || bestdiff > tmpdiff) {
+			bestrate = tmprate;
+			bestdiff = tmpdiff;
+		}
+
+		if (!bestdiff)
+			break;
+	}
+
+	return bestrate;
+}
+
+static int clk_utmi_set_rate(struct clk_hw *hw, unsigned long rate,
+			     unsigned long parent_rate)
+{
+	struct clk_utmi *utmi = to_clk_utmi(hw);
+	int i;
+
+	if (!utmi->sfr_regmap || !utmi->multipliers)
+		return rate == parent_rate * UTMI_FIXED_MUL ? 0 : -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(utmi_multipliers); i++) {
+		if (rate == parent_rate * utmi->multipliers[i]) {
+			regmap_update_bits(utmi->sfr_regmap, AT91_SFR_UTMICKTRIM,
+					   AT91_UTMICKTRIM_FREQ_MASK, i);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
 }
 
 static const struct clk_ops utmi_ops = {
@@ -75,10 +149,13 @@ static const struct clk_ops utmi_ops = {
 	.unprepare = clk_utmi_unprepare,
 	.is_prepared = clk_utmi_is_prepared,
 	.recalc_rate = clk_utmi_recalc_rate,
+	.round_rate = clk_utmi_round_rate,
+	.set_rate = clk_utmi_set_rate,
 };
 
 static struct clk_hw * __init
 at91_clk_register_utmi(struct regmap *regmap,
+		       struct regmap *sfr_regmap, const u8 *multipliers,
 		       const char *name, const char *parent_name)
 {
 	struct clk_utmi *utmi;
@@ -98,6 +175,8 @@ at91_clk_register_utmi(struct regmap *regmap,
 
 	utmi->hw.init = &init;
 	utmi->regmap = regmap;
+	utmi->sfr_regmap = sfr_regmap;
+	utmi->multipliers = multipliers;
 
 	hw = &utmi->hw;
 	ret = clk_hw_register(NULL, &utmi->hw);
@@ -115,6 +194,9 @@ static void __init of_at91sam9x5_clk_utmi_setup(struct device_node *np)
 	const char *parent_name;
 	const char *name = np->name;
 	struct regmap *regmap;
+	struct regmap *sfr_regmap;
+	const u8 *multipliers = NULL;
+	size_t i;
 
 	parent_name = of_clk_get_parent_name(np, 0);
 
@@ -124,7 +206,24 @@ static void __init of_at91sam9x5_clk_utmi_setup(struct device_node *np)
 	if (IS_ERR(regmap))
 		return;
 
-	hw = at91_clk_register_utmi(regmap, name, parent_name);
+	for (i = 0; i < ARRAY_SIZE(utmi_multipliers); i++) {
+		sfr_regmap = syscon_regmap_lookup_by_compatible(
+			utmi_multipliers[i].sfr_compatible_name);
+		if (!IS_ERR(sfr_regmap)) {
+			pr_debug("clk-utmi: found sfr node: %s\n",
+				 utmi_multipliers[i].sfr_compatible_name);
+			multipliers = utmi_multipliers[i].multipliers;
+			break;
+		}
+	}
+
+	if (IS_ERR(sfr_regmap)) {
+		pr_debug("clk-utmi: failed to find sfr node\n");
+		sfr_regmap = NULL;
+	}
+
+	hw = at91_clk_register_utmi(regmap, sfr_regmap, multipliers,
+				    name, parent_name);
 	if (IS_ERR(hw))
 		return;
 
diff --git a/include/soc/at91/atmel-sfr.h b/include/soc/at91/atmel-sfr.h
index 506ea8f..763948e 100644
--- a/include/soc/at91/atmel-sfr.h
+++ b/include/soc/at91/atmel-sfr.h
@@ -17,6 +17,7 @@
 /* 0x08 ~ 0x0c: Reserved */
 #define AT91_SFR_OHCIICR	0x10	/* OHCI INT Configuration Register */
 #define AT91_SFR_OHCIISR	0x14	/* OHCI INT Status Register */
+#define AT91_SFR_UTMICKTRIM	0x30	/* UTMI Clock Trimming Register */
 #define AT91_SFR_I2SCLKSEL	0x90	/* I2SC Register */
 
 /* Field definitions */
@@ -28,5 +29,6 @@
 					 AT91_OHCIICR_SUSPEND_B | \
 					 AT91_OHCIICR_SUSPEND_C)
 
+#define AT91_UTMICKTRIM_FREQ_MASK	0x03
 
 #endif /* _LINUX_MFD_SYSCON_ATMEL_SFR_H */
-- 
2.9.4