dm: Add a clock uclass

Clocks are an important feature of platforms and have become increasing
complex with time. Most modern SoCs have multiple PLLs and dozens of clock
dividers which distribute clocks to on-chip peripherals.

Some SoC implementations have a clock API which is private to that SoC family,
e.g. Tegra and Exynos. This is useful but it would be better to have a
common API that can be understood and used throughout U-Boot.

Add a simple clock API as a starting point. It supports querying and setting
the rate of a clock. Each clock is a device. To reduce memory and processing
overhead the concept of peripheral clocks is provided. These do not need to
be explicit devices - it is possible to write a driver that can adjust the
I2C clock (for example) without an explicit I2C clock device. This can
dramatically reduce the number of devices (and associated overhead) in a
complex SoC.

Clocks are referenced by a number, and it is expected that SoCs will define
that numbering themselves via an enum.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 64c27931aa3a0f792f0c2d206b8db7b6afc8be2a..092bc02b304ef6dc9f8cfd6230a5c1ebbf653618 100644 (file)
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -1,5 +1,7 @@
 menu "Device Drivers"
 
+source "drivers/clk/Kconfig"
+
 source "drivers/core/Kconfig"
 
 source "drivers/cpu/Kconfig"

diff --git a/drivers/Makefile b/drivers/Makefile
index 4f859dc30673c9c1df30a958049dbc2973da61fc..5a35148ead10237b81e570cc68ddc8b078c66b6c 100644 (file)
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -1,3 +1,4 @@
+obj-$(CONFIG_CLK) += clk/
 obj-$(CONFIG_DM) += core/
 obj-$(CONFIG_DM_DEMO) += demo/
 obj-$(CONFIG_BIOSEMU) += bios_emulator/

diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
new file mode 100644 (file)
index 0000000..07eb54c
--- /dev/null
+++ b/drivers/clk/Kconfig
@@ -0,0 +1,19 @@
+config CLK
+       bool "Enable clock driver support"
+       depends on DM
+       help
+         This allows drivers to be provided for clock generators, including
+         oscillators and PLLs. Devices can use a common clock API to request
+         a particular clock rate and check on available clocks. Clocks can
+         feed into other clocks in a tree structure, with multiplexers to
+         choose the source for each clock.
+
+config SPL_CLK_SUPPORT
+       bool "Enable clock support in SPL"
+       depends on CLK
+       help
+         The clock subsystem adds a small amount of overhead to the image.
+         If this is acceptable and you have a need to use clock drivers in
+         SPL, enable this option. It might provide a cleaner interface to
+         setting up clocks within SPL, and allows the same drivers to be
+         used as U-Boot proper.

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
new file mode 100644 (file)
index 0000000..b51cf23
--- /dev/null
+++ b/drivers/clk/Makefile
@@ -0,0 +1,8 @@
+#
+# Copyright (c) 2015 Google, Inc
+# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+#
+# SPDX-License-Identifier:      GPL-2.0+
+#
+
+obj-$(CONFIG_CLK) += clk-uclass.o

diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
new file mode 100644 (file)
index 0000000..73dfd7d
--- /dev/null
+++ b/drivers/clk/clk-uclass.c
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <errno.h>
+#include <dm/lists.h>
+#include <dm/root.h>
+
+ulong clk_get_rate(struct udevice *dev)
+{
+       struct clk_ops *ops = clk_get_ops(dev);
+
+       if (!ops->get_rate)
+               return -ENOSYS;
+
+       return ops->get_rate(dev);
+}
+
+ulong clk_set_rate(struct udevice *dev, ulong rate)
+{
+       struct clk_ops *ops = clk_get_ops(dev);
+
+       if (!ops->set_rate)
+               return -ENOSYS;
+
+       return ops->set_rate(dev, rate);
+}
+
+ulong clk_get_periph_rate(struct udevice *dev, int periph)
+{
+       struct clk_ops *ops = clk_get_ops(dev);
+
+       if (!ops->get_periph_rate)
+               return -ENOSYS;
+
+       return ops->get_periph_rate(dev, periph);
+}
+
+ulong clk_set_periph_rate(struct udevice *dev, int periph, ulong rate)
+{
+       struct clk_ops *ops = clk_get_ops(dev);
+
+       if (!ops->set_periph_rate)
+               return -ENOSYS;
+
+       return ops->set_periph_rate(dev, periph, rate);
+}
+
+UCLASS_DRIVER(clk) = {
+       .id             = UCLASS_CLK,
+       .name           = "clk",
+};

diff --git a/include/clk.h b/include/clk.h
index df4570c6f54abb0f5e6aac166b8096c19becdf69..254ad2b8761bf4acef3a5b4b06b3c6bc4c11ac11 100644 (file)
--- a/include/clk.h
+++ b/include/clk.h
@@ -1,6 +1,86 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
 #ifndef _CLK_H_
 #define _CLK_H_
 
 int soc_clk_dump(void);
 
+struct clk_ops {
+       /**
+        * get_rate() - Get current clock rate
+        *
+        * @dev:        Device to check (UCLASS_CLK)
+        * @return clock rate in Hz, or -ve error code
+        */
+       ulong (*get_rate)(struct udevice *dev);
+
+       /**
+        * set_rate() - Set current clock rate
+        *
+        * @dev:        Device to adjust
+        * @rate:       New clock rate in Hz
+        * @return new rate, or -ve error code
+        */
+       ulong (*set_rate)(struct udevice *dev, ulong rate);
+
+       /**
+       * clk_set_periph_rate() - Set clock rate for a peripheral
+       *
+       * @dev: Device to adjust (UCLASS_CLK)
+       * @rate:        New clock rate in Hz
+       * @return new clock rate in Hz, or -ve error code
+       */
+       ulong (*get_periph_rate)(struct udevice *dev, int periph);
+
+       /**
+        * clk_set_periph_rate() - Set current clock rate for a peripheral
+        *
+        * @dev:        Device to update (UCLASS_CLK)
+        * @periph:     Peripheral ID to cupdate
+        * @return new clock rate in Hz, or -ve error code
+        */
+       ulong (*set_periph_rate)(struct udevice *dev, int periph, ulong rate);
+};
+
+#define clk_get_ops(dev)       ((struct clk_ops *)(dev)->driver->ops)
+
+/**
+ * clk_get_rate() - Get current clock rate
+ *
+ * @dev:       Device to check (UCLASS_CLK)
+ * @return clock rate in Hz, or -ve error code
+ */
+ulong clk_get_rate(struct udevice *dev);
+
+/**
+ * set_rate() - Set current clock rate
+ *
+ * @dev:       Device to adjust
+ * @rate:      New clock rate in Hz
+ * @return new rate, or -ve error code
+ */
+ulong clk_set_rate(struct udevice *dev, ulong rate);
+
+/**
+ * clk_get_periph_rate() - Get current clock rate for a peripheral
+ *
+ * @dev:       Device to check (UCLASS_CLK)
+ * @return clock rate in Hz, -ve error code
+ */
+ulong clk_get_periph_rate(struct udevice *dev, int periph);
+
+/**
+ * clk_set_periph_rate() - Set current clock rate for a peripheral
+ *
+ * @dev:       Device to update (UCLASS_CLK)
+ * @periph:    Peripheral ID to cupdate
+ * @return new clock rate in Hz, or -ve error code
+ */
+ulong clk_set_periph_rate(struct udevice *dev, int periph, ulong rate);
+
 #endif /* _CLK_H_ */

diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index b993fc0a0639c87868c4c8e879d92a23d22e1eab..bc057d7adf05aa769f811bada96771a3b6a4f7e1 100644 (file)
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -25,6 +25,7 @@ enum uclass_id {
        UCLASS_SIMPLE_BUS,      /* bus with child devices */
 
        /* U-Boot uclasses start here - in alphabetical order */
+       UCLASS_CLK,             /* Clock source, e.g. used by peripherals */
        UCLASS_CPU,             /* CPU, typically part of an SoC */
        UCLASS_CROS_EC,         /* Chrome OS EC */
        UCLASS_DISPLAY_PORT,    /* Display port video */

diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
index 277958ad8e5e304c79cb7abc9ed9fff9ac39d141..525f9a238c64f49f3eb3c3a915749a5adf79f392 100644 (file)
--- a/scripts/Makefile.spl
+++ b/scripts/Makefile.spl
@@ -54,6 +54,7 @@ libs-$(HAVE_VENDOR_COMMON_LIB) += board/$(VENDOR)/common/
 libs-$(CONFIG_SPL_FRAMEWORK) += common/spl/
 libs-$(CONFIG_SPL_LIBCOMMON_SUPPORT) += common/
 libs-$(CONFIG_SPL_LIBDISK_SUPPORT) += disk/
+libs-$(CONFIG_SPL_CLK_SUPPORT) += drivers/clk/
 libs-$(CONFIG_SPL_DM) += drivers/core/
 libs-$(CONFIG_SPL_I2C_SUPPORT) += drivers/i2c/
 libs-$(CONFIG_SPL_GPIO_SUPPORT) += drivers/gpio/