clk: stm32f7: add clock driver for stm32f7 family

add basic clock driver support for stm32f7 to enable clocks required by
the peripherals.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/arm/mach-stm32/stm32f7/Makefile

@@ -5,4 +5,4 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-y += timer.o clock.o soc.o
+obj-y += timer.o soc.o

arch/arm/mach-stm32/stm32f7/soc.c

@@ -17,8 +17,6 @@ u32 get_cpu_rev(void)
 
 int arch_cpu_init(void)
 {
-	configure_clocks();
-
 	/*
 		* Configure the memory protection unit (MPU)
 		* 0x00000000 - 0xffffffff: Strong-order, Shareable

configs/stm32f746-disco_defconfig

@@ -39,3 +39,4 @@ CONFIG_DM_SPI=y
 CONFIG_STM32_QSPI=y
 CONFIG_OF_LIBFDT_OVERLAY=y
 # CONFIG_EFI_LOADER is not set
+CONFIG_CLK=y

doc/device-tree-bindings/clock/st,stm32-rcc.txt

@@ -0,0 +1,95 @@
+STMicroelectronics STM32 Reset and Clock Controller
+===================================================
+
+The RCC IP is both a reset and a clock controller.
+
+Please refer to clock-bindings.txt for common clock controller binding usage.
+Please also refer to reset.txt for common reset controller binding usage.
+
+Required properties:
+- compatible: Should be:
+  "st,stm32f42xx-rcc"
+  "st,stm32f469-rcc"
+- reg: should be register base and length as documented in the
+  datasheet
+- #reset-cells: 1, see below
+- #clock-cells: 2, device nodes should specify the clock in their "clocks"
+  property, containing a phandle to the clock device node, an index selecting
+  between gated clocks and other clocks and an index specifying the clock to
+  use.
+
+Example:
+
+	rcc: rcc@40023800 {
+		#reset-cells = <1>;
+		#clock-cells = <2>
+		compatible = "st,stm32f42xx-rcc", "st,stm32-rcc";
+		reg = <0x40023800 0x400>;
+	};
+
+Specifying gated clocks
+=======================
+
+The primary index must be set to 0.
+
+The secondary index is the bit number within the RCC register bank, starting
+from the first RCC clock enable register (RCC_AHB1ENR, address offset 0x30).
+
+It is calculated as: index = register_offset / 4 * 32 + bit_offset.
+Where bit_offset is the bit offset within the register (LSB is 0, MSB is 31).
+
+To simplify the usage and to share bit definition with the reset and clock
+drivers of the RCC IP, macros are available to generate the index in
+human-readble format.
+
+For STM32F4 series, the macro are available here:
+ - include/dt-bindings/mfd/stm32f4-rcc.h
+
+Example:
+
+	/* Gated clock, AHB1 bit 0 (GPIOA) */
+	... {
+		clocks = <&rcc 0 STM32F4_AHB1_CLOCK(GPIOA)>
+	};
+
+	/* Gated clock, AHB2 bit 4 (CRYP) */
+	... {
+		clocks = <&rcc 0 STM32F4_AHB2_CLOCK(CRYP)>
+	};
+
+Specifying other clocks
+=======================
+
+The primary index must be set to 1.
+
+The secondary index is bound with the following magic numbers:
+
+	0	SYSTICK
+	1	FCLK
+
+Example:
+
+	/* Misc clock, FCLK */
+	... {
+		clocks = <&rcc 1 STM32F4_APB1_CLOCK(TIM2)>
+	};
+
+
+Specifying softreset control of devices
+=======================================
+
+Device nodes should specify the reset channel required in their "resets"
+property, containing a phandle to the reset device node and an index specifying
+which channel to use.
+The index is the bit number within the RCC registers bank, starting from RCC
+base address.
+It is calculated as: index = register_offset / 4 * 32 + bit_offset.
+Where bit_offset is the bit offset within the register.
+For example, for CRC reset:
+  crc = AHB1RSTR_offset / 4 * 32 + CRCRST_bit_offset = 0x10 / 4 * 32 + 12 = 140
+
+example:
+
+	timer2 {
+		resets	= <&rcc STM32F4_APB1_RESET(TIM2)>;
+	};

drivers/clk/Makefile

@@ -18,5 +18,5 @@ obj-$(CONFIG_CLK_UNIPHIER) += uniphier/
 obj-$(CONFIG_CLK_EXYNOS) += exynos/
 obj-$(CONFIG_CLK_AT91) += at91/
 obj-$(CONFIG_CLK_BOSTON) += clk_boston.o
-
 obj-$(CONFIG_ARCH_ASPEED) += aspeed/
+obj-$(CONFIG_STM32F7) += clk_stm32f7.o

drivers/clk/clk_stm32f7.c

@@ -1,11 +1,12 @@
 /*
- * (C) Copyright 2016
+ * (C) Copyright 2017
  * Vikas Manocha, <vikas.manocha@st.com>
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
-
 #include <common.h>
+#include <clk-uclass.h>
+#include <dm.h>
 #include <asm/io.h>
 #include <asm/arch/rcc.h>
 #include <asm/arch/stm32.h>
@@ -212,6 +213,17 @@ unsigned long clock_get(enum clock clck)
 	}
 }
 
+static int stm32_clk_enable(struct clk *clk)
+{
+	u32 offset = clk->id / 32;
+	u32 bit_index = clk->id % 32;
+
+	debug("%s: clkid = %ld, offset from AHB1ENR is %d, bit_index = %d\n",
+	      __func__, clk->id, offset, bit_index);
+	setbits_le32(&STM32_RCC->ahb1enr + offset, BIT(bit_index));
+
+	return 0;
+}
 
 void clock_setup(int peripheral)
 {
@@ -273,3 +285,48 @@ void clock_setup(int peripheral)
 		break;
 	}
 }
+
+static int stm32_clk_probe(struct udevice *dev)
+{
+	debug("%s: stm32_clk_probe\n", __func__);
+	configure_clocks();
+
+	return 0;
+}
+
+static int stm32_clk_of_xlate(struct clk *clk,
+			struct fdtdec_phandle_args *args)
+{
+	debug("%s(clk=%p)\n", __func__, clk);
+
+	if (args->args_count != 2) {
+		debug("Invaild args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	if (args->args_count)
+		clk->id = args->args[1];
+	else
+		clk->id = 0;
+
+	return 0;
+}
+
+static struct clk_ops stm32_clk_ops = {
+	.of_xlate	= stm32_clk_of_xlate,
+	.enable		= stm32_clk_enable,
+};
+
+static const struct udevice_id stm32_clk_ids[] = {
+	{ .compatible = "st,stm32f42xx-rcc"},
+	{}
+};
+
+U_BOOT_DRIVER(stm32f7_clk) = {
+	.name		= "stm32f7_clk",
+	.id		= UCLASS_CLK,
+	.of_match	= stm32_clk_ids,
+	.ops		= &stm32_clk_ops,
+	.probe		= stm32_clk_probe,
+	.flags		= DM_FLAG_PRE_RELOC,
+};