Commit 7480e0aa authored by Rich Felker's avatar Rich Felker
Browse files

sh: add device tree support and generic board using device tree 



Add a new pseudo-board, within the existing SH boards/machine-vectors
framework, which does not represent any actual hardware but instead
requires all hardware to be described by the device tree blob provided
by the boot loader. Changes made are thus non-invasive and do not risk
breaking support for legacy boards.

New hardware, including the open-hardware J2 and associated SoC
devices, will use device free from the outset. Legacy SH boards can
transition to device tree once all their hardware has device tree
bindings, driver support for device tree, and a dts file for the
board.

It is intented that, once all boards are supported in the new
framework, the existing machine-vectors framework should be removed
and the new device tree setup code integrated directly.

Signed-off-by: default avatarRich Felker <dalias@libc.org>
parent 45624ac3

Documentation/devicetree/booting-without-of.txt

+13 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ Table of Contents 
    2) Entry point for arch/powerpc

    3) Entry point for arch/x86

    4) Entry point for arch/mips/bmips

    5) Entry point for arch/sh



  II - The DT block format

    1) Header
@@ -316,6 +317,18 @@ it with special cases. 
  This convention is defined for 32-bit systems only, as there are not

  currently any 64-bit BMIPS implementations.



5) Entry point for arch/sh

--------------------------



  Device-tree-compatible SH bootloaders are expected to provide the physical

  address of the device tree blob in r4. Since legacy bootloaders did not

  guarantee any particular initial register state, kernels built to

  inter-operate with old bootloaders must either use a builtin DTB or

  select a legacy board option (something other than CONFIG_SH_DEVICE_TREE)

  that does not use device tree. Support for the latter is being phased out

  in favor of device tree.





II - The DT block format

========================

arch/sh/boards/Kconfig

+15 −0
Original line number Diff line number Diff line
@@ -6,6 +6,21 @@ config SOLUTION_ENGINE 
config SH_ALPHA_BOARD

	bool



config SH_DEVICE_TREE

	bool "Board Described by Device Tree"

	select OF

	select OF_EARLY_FLATTREE

	select CLKSRC_OF

	select GENERIC_CALIBRATE_DELAY

	help

	  Select Board Described by Device Tree to build a kernel that

	  does not hard-code any board-specific knowledge but instead uses

	  a device tree blob provided by the boot-loader. You must enable

	  drivers for any hardware you want to use separately. At this

	  time, only boards based on the open-hardware J-Core processors

	  have sufficient driver coverage to use this option; do not

	  select it if you are using original SuperH hardware.



config SH_SOLUTION_ENGINE

	bool "SolutionEngine"

	select SOLUTION_ENGINE

arch/sh/boards/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -15,3 +15,5 @@ obj-$(CONFIG_SH_TITAN) += board-titan.o 
obj-$(CONFIG_SH_SH7757LCR)	+= board-sh7757lcr.o

obj-$(CONFIG_SH_APSH4A3A)	+= board-apsh4a3a.o

obj-$(CONFIG_SH_APSH4AD0A)	+= board-apsh4ad0a.o



obj-$(CONFIG_SH_DEVICE_TREE)	+= of-generic.o

arch/sh/boards/of-generic.c

0 → 100644
+113 −0
Original line number Diff line number Diff line 
/*

 * SH generic board support, using device tree

 *

 * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive

 * for more details.

 */



#include <linux/of.h>

#include <linux/of_platform.h>

#include <linux/of_fdt.h>

#include <linux/of_iommu.h>

#include <linux/clocksource.h>

#include <linux/irqchip.h>

#include <linux/clk-provider.h>

#include <asm/machvec.h>

#include <asm/rtc.h>



static void noop(void)

{

}



static int noopi(void)

{

	return 0;

}



static void __init sh_of_mem_reserve(void)

{

	early_init_fdt_reserve_self();

	early_init_fdt_scan_reserved_mem();

}



static void __init sh_of_time_init(void)

{

	pr_info("SH generic board support: scanning for clocksource devices\n");

	clocksource_probe();

}



static void __init sh_of_setup(char **cmdline_p)

{

	unflatten_device_tree();



	board_time_init = sh_of_time_init;



	sh_mv.mv_name = of_flat_dt_get_machine_name();

	if (!sh_mv.mv_name)

		sh_mv.mv_name = "Unknown SH model";



	/* FIXME: register smp ops to use dt to find cpus, use

	 * cpu enable-method, and use irq controller's ipi

	 * functions. */

}



static int sh_of_irq_demux(int irq)

{

	/* FIXME: eventually this should not be used at all;

	 * the interrupt controller should set_handle_irq(). */

	return irq;

}



static void __init sh_of_init_irq(void)

{

	pr_info("SH generic board support: scanning for interrupt controllers\n");

	irqchip_init();

}



static int __init sh_of_clk_init(void)

{

#ifdef CONFIG_COMMON_CLK

	/* Disabled pending move to COMMON_CLK framework. */

	pr_info("SH generic board support: scanning for clk providers\n");

	of_clk_init(NULL);

#endif

	return 0;

}



static struct sh_machine_vector __initmv sh_of_generic_mv = {

	.mv_setup	= sh_of_setup,

	.mv_name	= "devicetree", /* replaced by DT root's model */

	.mv_irq_demux	= sh_of_irq_demux,

	.mv_init_irq	= sh_of_init_irq,

	.mv_clk_init	= sh_of_clk_init,

	.mv_mode_pins	= noopi,

	.mv_mem_init	= noop,

	.mv_mem_reserve	= sh_of_mem_reserve,

};



struct sh_clk_ops;



void __init arch_init_clk_ops(struct sh_clk_ops **ops, int idx)

{

}



void __init plat_irq_setup(void)

{

}



static int __init sh_of_device_init(void)

{

	pr_info("SH generic board support: populating platform devices\n");

	if (of_have_populated_dt()) {

		of_iommu_init();

		of_platform_populate(NULL, of_default_bus_match_table,

				     NULL, NULL);

	} else {

		pr_crit("Device tree not populated\n");

	}

	return 0;

}

arch_initcall_sync(sh_of_device_init);

arch/sh/kernel/head_32.S

+13 −0
Original line number Diff line number Diff line
@@ -67,6 +67,10 @@ ENTRY(_stext) 
	ldc	r0, r6_bank

#endif



#ifdef CONFIG_OF

	mov	r4, r12		! Store device tree blob pointer in r12

#endif

	

	/*

	 * Prefetch if possible to reduce cache miss penalty.

	 *
@@ -314,6 +318,12 @@ ENTRY(_stext) 
10:		

#endif



#ifdef CONFIG_OF

	mov.l	8f, r0		! Make flat device tree available early.

	jsr	@r0

	 mov	r12, r4

#endif



	!			Additional CPU initialization

	mov.l	6f, r0

	jsr	@r0
@@ -339,6 +349,9 @@ ENTRY(stack_start) 
5:	.long	start_kernel

6:	.long	cpu_init

7:	.long	init_thread_union

#if defined(CONFIG_OF)

8:	.long	sh_fdt_init

#endif



#ifdef CONFIG_PMB

.LPMB_ADDR:		.long	PMB_ADDR

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