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From: Damien Le Moal <damien.lemoal@wdc.com>
To: linux-riscv@lists.infradead.org, Palmer Dabbelt <palmer@dabbelt.com>
Cc: Anup Patel <Anup.Patel@wdc.com>,
	Paul Walmsley <paul.walmsley@sifive.com>
Subject: [PATCH 05/10] riscv: Add SOC early init support
Date: Wed, 12 Feb 2020 19:34:27 +0900
Message-ID: <20200212103432.660256-6-damien.lemoal@wdc.com> (raw)
In-Reply-To: <20200212103432.660256-1-damien.lemoal@wdc.com>

Add a mechanism for early SoC initialization for platforms that need
additional hardware initialization not possible through the regular
device tree and drivers mechanism. With this, a SoC specific
initialization function can be called very early, before DTB parsing
is done by parse_dtb() in Linux RISC-V kernel setup code.

This can be very useful for early hardware initialization for No-MMU
kernels booted directly in M-mode because it is quite likely that no
other booting stage exist prior to the No-MMU kernel.

Example use of a SoC early initialization is as follows:

static void vendor_abc_early_init(const void *fdt)
{
	/*
	 * some early init code here that can use simple matches
	 * against the flat device tree file.
	 */
}
SOC_EARLY_INIT_DECLARE("vendor,abc", abc_early_init);

This early initialization function is executed only if the flat device
tree for the board has a 'compatible = "vendor,abc"' entry;

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/include/asm/soc.h    | 23 +++++++++++++++++++++++
 arch/riscv/kernel/Makefile      |  1 +
 arch/riscv/kernel/head.S        |  1 +
 arch/riscv/kernel/soc.c         | 28 ++++++++++++++++++++++++++++
 arch/riscv/kernel/vmlinux.lds.S |  6 ++++++
 5 files changed, 59 insertions(+)
 create mode 100644 arch/riscv/include/asm/soc.h
 create mode 100644 arch/riscv/kernel/soc.c

diff --git a/arch/riscv/include/asm/soc.h b/arch/riscv/include/asm/soc.h
new file mode 100644
index 000000000000..9b8c332cbe76
--- /dev/null
+++ b/arch/riscv/include/asm/soc.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+
+#ifndef _ASM_RISCV_SOC_H
+#define _ASM_RISCV_SOC_H
+
+#include <linux/of.h>
+#include <linux/linkage.h>
+#include <linux/types.h>
+
+#define SOC_EARLY_INIT_DECLARE(compat, fn)				\
+	static const struct of_device_id __soc_early_init		\
+		__used __section(__soc_early_init_table)		\
+		 = { .compatible = compat, .data = fn  }
+
+void soc_early_init(void);
+
+extern unsigned long __soc_early_init_table_start;
+extern unsigned long __soc_early_init_table_end;
+
+#endif
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 97d0c35f8b37..e4a22999dbc6 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -10,6 +10,7 @@ endif
 extra-y += head.o
 extra-y += vmlinux.lds
 
+obj-y	+= soc.o
 obj-y	+= cpu.o
 obj-y	+= cpufeature.o
 obj-y	+= entry.o
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 271860fc2c3f..a7768d6165d4 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -125,6 +125,7 @@ clear_bss_done:
 	call kasan_early_init
 #endif
 	/* Start the kernel */
+	call soc_early_init
 	call parse_dtb
 	tail start_kernel
 
diff --git a/arch/riscv/kernel/soc.c b/arch/riscv/kernel/soc.c
new file mode 100644
index 000000000000..0b3b3dc9ad0f
--- /dev/null
+++ b/arch/riscv/kernel/soc.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+#include <linux/init.h>
+#include <linux/libfdt.h>
+#include <asm/pgtable.h>
+#include <asm/soc.h>
+
+/*
+ * This is called extremly early, before parse_dtb(), to allow initializing
+ * SoC hardware before memory or any device driver initialization.
+ */
+void __init soc_early_init(void)
+{
+	void (*early_fn)(const void *fdt);
+	const struct of_device_id *s;
+	const void *fdt = dtb_early_va;
+
+	for (s = (void *)&__soc_early_init_table_start;
+	     (void *)s < (void *)&__soc_early_init_table_end; s++) {
+		if (!fdt_node_check_compatible(fdt, 0, s->compatible)) {
+			early_fn = s->data;
+			early_fn(fdt);
+			return;
+		}
+	}
+}
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 1e0193ded420..32b160942f40 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -24,6 +24,12 @@ SECTIONS
 	HEAD_TEXT_SECTION
 	INIT_TEXT_SECTION(PAGE_SIZE)
 	INIT_DATA_SECTION(16)
+	. = ALIGN(8);
+	__soc_early_init_table : {
+		__soc_early_init_table_start = .;
+		KEEP(*(__soc_early_init_table))
+		__soc_early_init_table_end = .;
+	}
 	/* we have to discard exit text and such at runtime, not link time */
 	.exit.text :
 	{
-- 
2.24.1



  parent reply index

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 10:34 [PATCH 00/10] Kendryte k210 SoC boards support Damien Le Moal
2020-02-12 10:34 ` [PATCH 01/10] riscv: Fix gitignore Damien Le Moal
2020-02-20  0:15   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 02/10] riscv: Force flat memory model with no-mmu Damien Le Moal
2020-02-14 20:18   ` Sean Anderson
2020-02-15  2:15     ` Damien Le Moal
2020-02-15  2:26       ` Sean Anderson
2020-02-15  2:40         ` Damien Le Moal
2020-03-02  3:48   ` Anup Patel
2020-03-04 18:38   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 03/10] riscv: Unaligned load/store handling for M_MODE Damien Le Moal
2020-03-02  3:57   ` Anup Patel
2020-03-04 19:28   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 04/10] riscv: Add BUILTIN_DTB support Damien Le Moal
2020-03-02  3:58   ` Anup Patel
2020-03-04 19:28   ` Palmer Dabbelt
2020-03-05  4:58     ` Anup Patel
2020-03-05  5:14       ` Damien Le Moal
2020-03-05  5:37         ` Anup Patel
2020-03-05  6:13           ` Damien Le Moal
2020-03-08  6:10             ` Anup Patel
2020-03-05  8:18         ` Atish Patra
2020-03-07  0:02           ` Sean Anderson
2020-03-07  1:51             ` Atish Patra
2020-03-07  2:08               ` Sean Anderson
2020-03-06 23:56         ` Sean Anderson
2020-02-12 10:34 ` Damien Le Moal [this message]
2020-03-04 19:28   ` [PATCH 05/10] riscv: Add SOC early init support Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 06/10] riscv: Add Kendryte K210 SoC support Damien Le Moal
2020-02-14 20:31   ` Sean Anderson
2020-03-04 19:38   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 07/10] riscv: Select required drivers for Kendryte SOC Damien Le Moal
2020-03-02  3:59   ` Anup Patel
2020-03-04 19:44   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 08/10] riscv: Add Kendryte K210 device tree Damien Le Moal
2020-02-14 20:51   ` Sean Anderson
2020-02-15  2:34     ` Damien Le Moal
2020-02-15  2:48       ` Sean Anderson
2020-02-15  3:00         ` Damien Le Moal
2020-02-18 14:12           ` Carlos Eduardo de Paula
2020-02-18 14:18             ` Sean Anderson
2020-02-18 14:30               ` Carlos Eduardo de Paula
2020-02-18 17:48                 ` Sean Anderson
2020-02-18 19:26                   ` Carlos Eduardo de Paula
2020-02-19  9:06                     ` Wladimir J. van der Laan
2020-02-19 22:28                       ` Sean Anderson
2020-02-20 10:48                         ` Wladimir J. van der Laan
2020-02-22 19:07                       ` Wladimir J. van der Laan
2020-04-01 17:55                         ` Drew Fustini
2020-04-02  2:24                           ` Damien Le Moal
2020-02-19  8:50                   ` Wladimir J. van der Laan
2020-02-27 19:43       ` Sean Anderson
2020-03-02  4:06   ` Anup Patel
2020-03-02  4:15     ` Damien Le Moal
2020-03-02  4:22       ` Anup Patel
2020-03-02  4:51         ` Damien Le Moal
2020-03-02  5:05           ` Anup Patel
2020-03-02  5:08             ` Damien Le Moal
2020-03-07  0:18               ` Sean Anderson
2020-03-07  4:11                 ` Anup Patel
2020-03-04 19:44   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 09/10] riscv: Kendryte K210 default config Damien Le Moal
2020-03-02  4:07   ` Anup Patel
2020-03-04 19:44   ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 10/10] riscv: create a loader.bin for the kendryte kflash.py tool Damien Le Moal
2020-03-02  4:08   ` Anup Patel
2020-03-04 19:44   ` Palmer Dabbelt
2020-02-14 15:05 ` [PATCH 00/10] Kendryte k210 SoC boards support Carlos Eduardo de Paula
2020-02-15  2:02   ` Damien Le Moal
2020-02-17 13:28     ` Carlos Eduardo de Paula
2020-02-26 21:31       ` Carlos Eduardo de Paula
2020-02-27  2:18         ` Damien Le Moal
2020-02-28 20:32 ` Sean Anderson
2020-03-02  3:01   ` Damien Le Moal
2020-03-02  3:53     ` Sean Anderson
2020-03-02  4:11       ` Damien Le Moal
2020-03-02  4:18         ` Sean Anderson
2020-03-02  4:54           ` Damien Le Moal
2020-03-02  4:56             ` Sean Anderson
2020-03-02  5:03               ` Damien Le Moal
2020-03-02  4:17       ` Anup Patel
2020-03-02  4:21         ` Sean Anderson
2020-03-02  4:48         ` Damien Le Moal
2020-03-02  4:51           ` Damien Le Moal
2020-03-02  5:02           ` Sean Anderson
2020-03-02  5:11             ` Damien Le Moal
2020-03-02  5:25               ` Sean Anderson
2020-03-02  5:43                 ` Damien Le Moal
2020-03-04 19:44 ` Palmer Dabbelt

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