clk: at91: utmi: Set the reference clock frequency

By default, it is assumed that the UTMI clock is generated from
a 12 MHz reference clock (MAINCK). If it's not the case, the FREQ
field of the SFR_UTMICKTRIM has to be updated to generate the UTMI
clock in the proper way.

The UTMI clock has a fixed rate of 480 MHz. In fact, there is no
multiplier we can configure. The multiplier is managed internally,
depending on the reference clock frequency, to achieve the target
of 480 MHz.

The patch is cloned from the patch of mailing-list:
	[PATCH v2] clk: at91: utmi: set the mainck rate

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
[trini: Depend on SPL_DM]
Signed-off-by: Tom Rini <trini@konsulko.com>

arch/arm/mach-at91/include/mach/sama5_sfr.h

@@ -28,6 +28,9 @@ struct atmel_sfr {
 	u32 l2cc_hramc;	/* 0x58 */
 };
 
+/* Register Mapping*/
+#define AT91_SFR_UTMICKTRIM	0x30	/* UTMI Clock Trimming Register */
+
 /* Bit field in DDRCFG */
 #define ATMEL_SFR_DDRCFG_FDQIEN		0x00010000
 #define ATMEL_SFR_DDRCFG_FDQSIEN	0x00020000
@@ -56,6 +59,8 @@ struct atmel_sfr {
 #define AT91_SFR_EBICFG_SCH1_OFF		(0x0 << 12)
 #define AT91_SFR_EBICFG_SCH1_ON			(0x1 << 12)
 
+#define AT91_UTMICKTRIM_FREQ		GENMASK(1, 0)
+
 /* Bit field in AICREDIR */
 #define ATMEL_SFR_AICREDIR_NSAIC	0x00000001
 

drivers/clk/at91/Kconfig

@@ -14,7 +14,11 @@ config CLK_AT91
 
 config AT91_UTMI
 	bool "Support UTMI PLL Clock"
-	depends on CLK_AT91
+	depends on CLK_AT91 && SPL_DM
+	select REGMAP
+	select SPL_REGMAP
+	select SYSCON
+	select SPL_SYSCON
 	help
 	  This option is used to enable the AT91 UTMI PLL clock
 	  driver. It is the clock provider of USB, and UPLLCK is the

drivers/clk/at91/clk-utmi.c

@@ -8,23 +8,80 @@
 #include <common.h>
 #include <clk-uclass.h>
 #include <dm.h>
+#include <syscon.h>
 #include <linux/io.h>
 #include <mach/at91_pmc.h>
+#include <mach/sama5_sfr.h>
 #include "pmc.h"
 
 DECLARE_GLOBAL_DATA_PTR;
 
-#define UTMI_FIXED_MUL		40
+/*
+ * The purpose of this clock is to generate a 480 MHz signal. A different
+ * rate can't be configured.
+ */
+#define UTMI_RATE	480000000
 
 static int utmi_clk_enable(struct clk *clk)
 {
 	struct pmc_platdata *plat = dev_get_platdata(clk->dev);
 	struct at91_pmc *pmc = plat->reg_base;
+	struct clk clk_dev;
+	ulong clk_rate;
+	u32 utmi_ref_clk_freq;
 	u32 tmp;
+	int err;
 
 	if (readl(&pmc->sr) & AT91_PMC_LOCKU)
 		return 0;
 
+	/*
+	 * If mainck rate is different from 12 MHz, we have to configure the
+	 * FREQ field of the SFR_UTMICKTRIM register to generate properly
+	 * the utmi clock.
+	 */
+	err = clk_get_by_index(clk->dev, 0, &clk_dev);
+	if (err)
+		return -EINVAL;
+
+	clk_rate = clk_get_rate(&clk_dev);
+	switch (clk_rate) {
+	case 12000000:
+		utmi_ref_clk_freq = 0;
+		break;
+	case 16000000:
+		utmi_ref_clk_freq = 1;
+		break;
+	case 24000000:
+		utmi_ref_clk_freq = 2;
+		break;
+	/*
+	 * Not supported on SAMA5D2 but it's not an issue since MAINCK
+	 * maximum value is 24 MHz.
+	 */
+	case 48000000:
+		utmi_ref_clk_freq = 3;
+		break;
+	default:
+		printf("UTMICK: unsupported mainck rate\n");
+		return -EINVAL;
+	}
+
+	if (plat->regmap_sfr) {
+		err = regmap_read(plat->regmap_sfr, AT91_SFR_UTMICKTRIM, &tmp);
+		if (err)
+			return -EINVAL;
+
+		tmp &= ~AT91_UTMICKTRIM_FREQ;
+		tmp |= utmi_ref_clk_freq;
+		err = regmap_write(plat->regmap_sfr, AT91_SFR_UTMICKTRIM, tmp);
+		if (err)
+			return -EINVAL;
+	} else if (utmi_ref_clk_freq) {
+		printf("UTMICK: sfr node required\n");
+		return -EINVAL;
+	}
+
 	tmp = readl(&pmc->uckr);
 	tmp |= AT91_PMC_UPLLEN |
 	       AT91_PMC_UPLLCOUNT |
@@ -39,7 +96,8 @@ static int utmi_clk_enable(struct clk *clk)
 
 static ulong utmi_clk_get_rate(struct clk *clk)
 {
-	return gd->arch.main_clk_rate_hz * UTMI_FIXED_MUL;
+	/* UTMI clk rate is fixed. */
+	return UTMI_RATE;
 }
 
 static struct clk_ops utmi_clk_ops = {
@@ -47,6 +105,20 @@ static struct clk_ops utmi_clk_ops = {
 	.get_rate = utmi_clk_get_rate,
 };
 
+static int utmi_clk_ofdata_to_platdata(struct udevice *dev)
+{
+	struct pmc_platdata *plat = dev_get_platdata(dev);
+	struct udevice *syscon;
+
+	uclass_get_device_by_phandle(UCLASS_SYSCON, dev,
+				     "regmap-sfr", &syscon);
+
+	if (syscon)
+		plat->regmap_sfr = syscon_get_regmap(syscon);
+
+	return 0;
+}
+
 static int utmi_clk_probe(struct udevice *dev)
 {
 	return at91_pmc_core_probe(dev);
@@ -62,6 +134,7 @@ U_BOOT_DRIVER(at91sam9x5_utmi_clk) = {
 	.id = UCLASS_CLK,
 	.of_match = utmi_clk_match,
 	.probe = utmi_clk_probe,
+	.ofdata_to_platdata = utmi_clk_ofdata_to_platdata,
 	.platdata_auto_alloc_size = sizeof(struct pmc_platdata),
 	.ops = &utmi_clk_ops,
 };

drivers/clk/at91/pmc.h

@@ -8,8 +8,11 @@
 #ifndef __AT91_PMC_H__
 #define __AT91_PMC_H__
 
+#include <regmap.h>
+
 struct pmc_platdata {
 	struct at91_pmc *reg_base;
+	struct regmap *regmap_sfr;
 };
 
 int at91_pmc_core_probe(struct udevice *dev);