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Date: Fri, 12 Apr 2024 12:30:32 +0100
From: Conor Dooley <conor.dooley@microchip.com>
To: Charlie Jenkins <charlie@rivosinc.com>
CC: Conor Dooley <conor@kernel.org>, Rob Herring <robh@kernel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Paul Walmsley
	<paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou
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	<shuah@kernel.org>, <linux-riscv@lists.infradead.org>,
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Subject: Re: [PATCH 12/19] riscv: Create xtheadvector file
Message-ID: <20240412-thirty-sacrament-db052c7fe6fe@wendy>
References: <20240411-dev-charlie-support_thead_vector_6_9-v1-0-4af9815ec746@rivosinc.com>
 <20240411-dev-charlie-support_thead_vector_6_9-v1-12-4af9815ec746@rivosinc.com>
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On Thu, Apr 11, 2024 at 09:11:18PM -0700, Charlie Jenkins wrote:
> These definitions didn't fit anywhere nicely, so create a new file to
> house various xtheadvector instruction encodings.
>=20
> Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
>  arch/riscv/include/asm/xtheadvector.h | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>=20
> diff --git a/arch/riscv/include/asm/xtheadvector.h b/arch/riscv/include/a=
sm/xtheadvector.h
> new file mode 100644
> index 000000000000..348263ea164c
> --- /dev/null
> +++ b/arch/riscv/include/asm/xtheadvector.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +/*
> + * Vector 0.7.1 as used for example on T-Head Xuantie cores, uses an old=
er
> + * encoding for vsetvli (ta, ma vs. d1), so provide an instruction for
> + * vsetvli	t4, x0, e8, m8, d1
> + */
> +#define THEAD_VSETVLI_T4X0E8M8D1	".long	0x00307ed7\n\t"
> +#define THEAD_VSETVLI_X0X0E8M8D1	".long	0x00307057\n\t"
> +
> +/*
> + * While in theory, the vector-0.7.1 vsb.v and vlb.v result in the same
> + * encoding as the standard vse8.v and vle8.v, compilers seem to optimize
> + * the call resulting in a different encoding and then using a value for
> + * the "mop" field that is not part of vector-0.7.1
> + * So encode specific variants for vstate_save and _restore.

This wording seems oddly familiar to me, did Heiko not write this?

> + */
> +#define THEAD_VSB_V_V0T0		".long	0x02028027\n\t"
> +#define THEAD_VSB_V_V8T0		".long	0x02028427\n\t"
> +#define THEAD_VSB_V_V16T0		".long	0x02028827\n\t"
> +#define THEAD_VSB_V_V24T0		".long	0x02028c27\n\t"
> +#define THEAD_VLB_V_V0T0		".long	0x012028007\n\t"
> +#define THEAD_VLB_V_V8T0		".long	0x012028407\n\t"
> +#define THEAD_VLB_V_V16T0		".long	0x012028807\n\t"
> +#define THEAD_VLB_V_V24T0		".long	0x012028c07\n\t"
>=20
> --=20
> 2.44.0
>=20

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