From: Christoph Hellwig <hch@lst.de>
To: Palmer Dabbelt <palmer@sifive.com>,
Paul Walmsley <paul.walmsley@sifive.com>
Cc: Anup Patel <anup@brainfault.org>,
Damien Le Moal <damien.lemoal@wdc.com>,
Atish Patra <atish.patra@wdc.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 08/12] riscv: read the hart ID from mhartid on boot
Date: Mon, 28 Oct 2019 13:10:39 +0100 [thread overview]
Message-ID: <20191028121043.22934-9-hch@lst.de> (raw)
In-Reply-To: <20191028121043.22934-1-hch@lst.de>
From: Damien Le Moal <damien.lemoal@wdc.com>
When in M-Mode, we can use the mhartid CSR to get the ID of the running
HART. Doing so, direct M-Mode boot without firmware is possible.
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
arch/riscv/include/asm/csr.h | 1 +
arch/riscv/kernel/head.S | 8 ++++++++
2 files changed, 9 insertions(+)
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 0ab642811028..318192c66fd8 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -99,6 +99,7 @@
#define CSR_MCAUSE 0x342
#define CSR_MTVAL 0x343
#define CSR_MIP 0x344
+#define CSR_MHARTID 0xf14
#ifdef CONFIG_RISCV_M_MODE
# define CSR_STATUS CSR_MSTATUS
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 5cfd2c582945..fc9973086946 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -50,6 +50,14 @@ _start_kernel:
csrw CSR_IE, zero
csrw CSR_IP, zero
+#ifdef CONFIG_RISCV_M_MODE
+ /*
+ * The hartid in a0 is expected later on, and we have no firmware
+ * to hand it to us.
+ */
+ csrr a0, CSR_MHARTID
+#endif
+
/* Load the global pointer */
.option push
.option norelax
--
2.20.1
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next prev parent reply other threads:[~2019-10-28 12:11 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-28 12:10 RISC-V nommu support v6 Christoph Hellwig
2019-10-28 12:10 ` [PATCH 01/12] riscv: abstract out CSR names for supervisor vs machine mode Christoph Hellwig
2019-11-05 17:56 ` Paul Walmsley
2019-11-05 17:57 ` Paul Walmsley
2019-11-05 18:02 ` Marc Zyngier
2019-11-12 10:38 ` Thomas Gleixner
2019-11-14 7:30 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 02/12] riscv: don't allow selecting SBI based drivers for M-mode Christoph Hellwig
2019-11-14 7:31 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 03/12] riscv: poison SBI calls " Christoph Hellwig
2019-10-31 23:55 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 04/12] riscv: cleanup the default power off implementation Christoph Hellwig
2019-10-31 20:49 ` Paul Walmsley
2019-10-31 23:56 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 05/12] riscv: implement remote sfence.i using IPIs Christoph Hellwig
2019-10-31 23:57 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 06/12] riscv: add support for MMIO access to the timer registers Christoph Hellwig
2019-11-05 18:01 ` Paul Walmsley
2019-11-12 10:39 ` Thomas Gleixner
2019-11-17 23:06 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 07/12] riscv: provide native clint access for M-mode Christoph Hellwig
2019-10-28 12:10 ` Christoph Hellwig [this message]
2019-10-28 12:10 ` [PATCH 09/12] riscv: clear the instruction cache and all registers when booting Christoph Hellwig
2019-11-14 7:45 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 10/12] riscv: add nommu support Christoph Hellwig
2019-11-17 23:13 ` Paul Walmsley
2019-12-16 22:03 ` David Abdurachmanov
2019-12-17 3:18 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 11/12] riscv: provide a flat image loader Christoph Hellwig
2019-11-17 23:14 ` Paul Walmsley
2019-10-28 12:10 ` [PATCH 12/12] riscv: disable the EFI PECOFF header for M-mode Christoph Hellwig
2019-10-30 20:21 ` RISC-V nommu support v6 Paul Walmsley
2019-10-31 15:52 ` Christoph Hellwig
2019-10-31 20:13 ` Paul Walmsley
2019-11-23 2:19 ` Paul Walmsley
2019-12-11 8:42 ` Greentime Hu
2020-02-12 12:19 ` Greentime Hu
2019-11-11 9:47 ` Christoph Hellwig
2019-11-11 17:02 ` Paul Walmsley
2019-11-13 13:18 ` Christoph Hellwig
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