From: Christoph Hellwig <hch@lst.de>
To: Palmer Dabbelt <palmer@sifive.com>,
Paul Walmsley <paul.walmsley@sifive.com>
Cc: Atish Patra <atish.patra@wdc.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 07/15] riscv: read the hart ID from mhartid on boot
Date: Tue, 13 Aug 2019 17:47:39 +0200 [thread overview]
Message-ID: <20190813154747.24256-8-hch@lst.de> (raw)
In-Reply-To: <20190813154747.24256-1-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>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
---
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 53d7ce74b447..64f8fe84b88f 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -81,6 +81,7 @@
#define SIE_SEIE (_AC(0x1, UL) << IRQ_S_EXT)
/* symbolic CSR names: */
+#define CSR_MHARTID 0xf14
#define CSR_MSTATUS 0x300
#define CSR_MIE 0x304
#define CSR_MTVEC 0x305
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index bb96bb7b95d2..275c2ab1e990 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -50,6 +50,14 @@ _start_kernel:
csrw CSR_XIE, zero
csrw CSR_XIP, zero
+#ifdef CONFIG_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:[~2019-08-13 15:48 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-13 15:47 RISC-V nommu support v3 Christoph Hellwig
2019-08-13 15:47 ` [PATCH 01/15] irqchip/sifive-plic: set max threshold for ignored handlers Christoph Hellwig
2019-08-13 17:44 ` Paul Walmsley
2019-08-14 9:06 ` Marc Zyngier
2019-08-13 15:47 ` [PATCH 02/15] riscv: use CSR_SATP instead of the legacy sptbr name in switch_mm Christoph Hellwig
2019-08-13 16:36 ` Paul Walmsley
2019-08-13 16:42 ` Christoph Hellwig
2019-08-13 16:51 ` Paul Walmsley
2019-08-13 19:44 ` Paul Walmsley
2019-08-13 15:47 ` [PATCH 03/15] riscv: refactor the IPI code Christoph Hellwig
2019-08-14 4:41 ` Paul Walmsley
2019-08-19 10:18 ` Christoph Hellwig
2019-09-01 8:03 ` Christoph Hellwig
2019-08-13 15:47 ` [PATCH 04/15] riscv: abstract out CSR names for supervisor vs machine mode Christoph Hellwig
2019-08-13 15:47 ` [PATCH 05/15] riscv: improve the default power off implementation Christoph Hellwig
2019-08-13 15:47 ` [PATCH 06/15] riscv: provide a flat entry loader Christoph Hellwig
2019-08-13 15:47 ` Christoph Hellwig [this message]
2019-08-13 15:47 ` [PATCH 08/15] riscv: provide native clint access for M-mode Christoph Hellwig
2019-08-13 16:29 ` Mark Rutland
2019-08-19 10:16 ` Christoph Hellwig
2019-08-27 23:37 ` Palmer Dabbelt
2019-08-28 6:11 ` Christoph Hellwig
2019-09-03 18:48 ` Palmer Dabbelt
2019-09-04 2:05 ` Alan Kao
2019-08-21 0:24 ` Atish Patra
2019-08-21 0:42 ` hch
2019-08-13 15:47 ` [PATCH 09/15] riscv: implement remote sfence.i natively " Christoph Hellwig
2019-08-20 21:04 ` Atish Patra
2019-08-13 15:47 ` [PATCH 10/15] riscv: poison SBI calls " Christoph Hellwig
2019-08-20 21:05 ` Atish Patra
2019-08-13 15:47 ` [PATCH 11/15] riscv: don't allow selecting SBI-based drivers " Christoph Hellwig
2019-08-13 15:47 ` [PATCH 12/15] riscv: use the correct interrupt levels " Christoph Hellwig
2019-08-13 15:47 ` [PATCH 13/15] riscv: clear the instruction cache and all registers when booting Christoph Hellwig
2019-08-14 1:00 ` Alan Kao
2019-08-14 1:07 ` Alan Kao
2019-08-14 4:35 ` Christoph Hellwig
2019-08-13 15:47 ` [PATCH 14/15] riscv: add nommu support Christoph Hellwig
2019-08-13 15:47 ` [PATCH 15/15] riscv: disable the EFI PECOFF header for M-mode Christoph Hellwig
2019-08-20 21:07 ` Atish Patra
2019-08-21 4:14 ` Troy Benjegerdes
2019-08-21 7:12 ` Christoph Hellwig
2019-08-21 17:31 ` Atish Patra
2019-08-21 17:54 ` Troy Benjegerdes
2019-08-21 23:02 ` Anup Patel
2019-08-21 23:32 ` Troy Benjegerdes
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