clk: sunxi-ng: Allow the CCU core to be built as a module

Like the individual CCU drivers, it can be beneficial for memory
consumption of cross-platform configurations to only load the CCU core
on the relevant platform. For example, a generic arm64 kernel sees the
following improvement when building the CCU core and drivers as modules:

  before:
    text      data     bss     dec       hex      filename
    13882360  5251670  360800  19494830  12977ae  vmlinux

  after:
    text      data     bss     dec       hex      filename
    13734787  5086442  360800  19182029  124b1cd  vmlinux

So the result is a 390KB total reduction in kernel image size.

The one early clock provider (sun5i) requires the core to be built in.

Now that loading the MMC driver will trigger loading the CCU core, the
MMC timing mode functions do not need a compile-time fallback.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20211119033338.25486-5-samuel@sholland.org

drivers/clk/Makefile

@@ -110,7 +110,7 @@ obj-$(CONFIG_PLAT_SPEAR)		+= spear/
 obj-y					+= sprd/
 obj-$(CONFIG_ARCH_STI)			+= st/
 obj-$(CONFIG_ARCH_SUNXI)		+= sunxi/
-obj-$(CONFIG_SUNXI_CCU)			+= sunxi-ng/
+obj-y					+= sunxi-ng/
 obj-$(CONFIG_ARCH_TEGRA)		+= tegra/
 obj-y					+= ti/
 obj-$(CONFIG_CLK_UNIPHIER)		+= uniphier/

drivers/clk/sunxi-ng/Kconfig

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 config SUNXI_CCU
-	bool "Clock support for Allwinner SoCs"
+	tristate "Clock support for Allwinner SoCs"
 	depends on ARCH_SUNXI || COMPILE_TEST
 	select RESET_CONTROLLER
 	default ARCH_SUNXI
@@ -52,6 +52,7 @@ config SUN5I_CCU
 	bool "Support for the Allwinner sun5i family CCM"
 	default MACH_SUN5I
 	depends on MACH_SUN5I || COMPILE_TEST
+	depends on SUNXI_CCU=y
 
 config SUN6I_A31_CCU
 	tristate "Support for the Allwinner A31/A31s CCU"

drivers/clk/sunxi-ng/Makefile

@@ -1,24 +1,27 @@
 # SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_SUNXI_CCU)		+= sunxi-ccu.o
+
 # Common objects
-obj-y				+= ccu_common.o
-obj-y				+= ccu_mmc_timing.o
-obj-y				+= ccu_reset.o
+sunxi-ccu-y			+= ccu_common.o
+sunxi-ccu-y			+= ccu_mmc_timing.o
+sunxi-ccu-y			+= ccu_reset.o
 
 # Base clock types
-obj-y				+= ccu_div.o
-obj-y				+= ccu_frac.o
-obj-y				+= ccu_gate.o
-obj-y				+= ccu_mux.o
-obj-y				+= ccu_mult.o
-obj-y				+= ccu_phase.o
-obj-y				+= ccu_sdm.o
+sunxi-ccu-y			+= ccu_div.o
+sunxi-ccu-y			+= ccu_frac.o
+sunxi-ccu-y			+= ccu_gate.o
+sunxi-ccu-y			+= ccu_mux.o
+sunxi-ccu-y			+= ccu_mult.o
+sunxi-ccu-y			+= ccu_phase.o
+sunxi-ccu-y			+= ccu_sdm.o
 
 # Multi-factor clocks
-obj-y				+= ccu_nk.o
-obj-y				+= ccu_nkm.o
-obj-y				+= ccu_nkmp.o
-obj-y				+= ccu_nm.o
-obj-y				+= ccu_mp.o
+sunxi-ccu-y			+= ccu_nk.o
+sunxi-ccu-y			+= ccu_nkm.o
+sunxi-ccu-y			+= ccu_nkmp.o
+sunxi-ccu-y			+= ccu_nm.o
+sunxi-ccu-y			+= ccu_mp.o
 
 # SoC support
 obj-$(CONFIG_SUNIV_F1C100S_CCU)	+= suniv-f1c100s-ccu.o

drivers/clk/sunxi-ng/ccu_common.c

@@ -9,6 +9,7 @@
 #include <linux/clk-provider.h>
 #include <linux/device.h>
 #include <linux/iopoll.h>
+#include <linux/module.h>
 #include <linux/slab.h>
 
 #include "ccu_common.h"
@@ -214,3 +215,5 @@ void of_sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
 		kfree(ccu);
 	}
 }
+
+MODULE_LICENSE("GPL");

drivers/mmc/host/Kconfig

@@ -966,6 +966,7 @@ config MMC_REALTEK_USB
 config MMC_SUNXI
 	tristate "Allwinner sunxi SD/MMC Host Controller support"
 	depends on ARCH_SUNXI || COMPILE_TEST
+	depends on SUNXI_CCU
 	help
 	  This selects support for the SD/MMC Host Controller on
 	  Allwinner sunxi SoCs.

include/linux/clk/sunxi-ng.h

@@ -6,22 +6,7 @@
 #ifndef _LINUX_CLK_SUNXI_NG_H_
 #define _LINUX_CLK_SUNXI_NG_H_
 
-#include <linux/errno.h>
-
-#ifdef CONFIG_SUNXI_CCU
 int sunxi_ccu_set_mmc_timing_mode(struct clk *clk, bool new_mode);
 int sunxi_ccu_get_mmc_timing_mode(struct clk *clk);
-#else
-static inline int sunxi_ccu_set_mmc_timing_mode(struct clk *clk,
-						bool new_mode)
-{
-	return -ENOTSUPP;
-}
-
-static inline int sunxi_ccu_get_mmc_timing_mode(struct clk *clk)
-{
-	return -ENOTSUPP;
-}
-#endif
 
 #endif