Re: [PATCH v6 04/21] RISC-V: Define indirect CSR access helpers

[Atish Patra]

On 6/21/26 11:42 PM, Charlie Jenkins wrote:
> On Mon, Jun 08, 2026 at 11:01:18PM -0700, Atish Patra wrote:
> > From: Atish Patra <atishp@xxxxxxxxxxxx>
> >
> > The indriect CSR requires multiple instructions to read/write CSR.
> indirect
>
> > Add a few helper functions for ease of usage.
> >
> > Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
> > ---
> >   arch/riscv/include/asm/csr_ind.h | 44 ++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 44 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/csr_ind.h b/arch/riscv/include/asm/csr_ind.h
> > new file mode 100644
> > index 000000000000..6fd7d44dc640
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/csr_ind.h
> > @@ -0,0 +1,44 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2024 Rivos Inc.
> I don't think it makes sense to introduce this copyright in new commits.
Yeah. I will update these.
> - Charlie
>
> > + */
> > +
> > +#ifndef _ASM_RISCV_CSR_IND_H
> > +#define _ASM_RISCV_CSR_IND_H
> > +
> > +#include <linux/irqflags.h>
> > +
> > +#include <asm/csr.h>
> > +
> > +#define csr_ind_read(iregcsr, iselbase, iseloff) ({		\
> > +	unsigned long __value = 0;				\
> > +	unsigned long __flags;					\
> > +	local_irq_save(__flags);				\
> > +	csr_write(CSR_ISELECT, (iselbase) + (iseloff));		\
> > +	__value = csr_read(iregcsr);				\
> > +	local_irq_restore(__flags);				\
> > +	__value;						\
> > +})
> > +
> > +#define csr_ind_write(iregcsr, iselbase, iseloff, value) ({	\
> > +	unsigned long __flags;					\
> > +	local_irq_save(__flags);				\
> > +	csr_write(CSR_ISELECT, (iselbase) + (iseloff));		\
> > +	csr_write(iregcsr, (value));				\
> > +	local_irq_restore(__flags);				\
> > +})
> > +
> > +#define csr_ind_warl(iregcsr, iselbase, iseloff, warl_val) ({	\
> > +	unsigned long __old_val = 0, __value = 0;		\
> > +	unsigned long __flags;					\
> > +	local_irq_save(__flags);				\
> > +	csr_write(CSR_ISELECT, (iselbase) + (iseloff));		\
> > +	__old_val = csr_read(iregcsr);				\
> > +	csr_write(iregcsr, (warl_val));				\
> > +	__value = csr_read(iregcsr);				\
> > +	csr_write(iregcsr, __old_val);				\
> > +	local_irq_restore(__flags);				\
> > +	__value;						\
> > +})
> > +
> > +#endif
> >
> > --
> > 2.53.0-Meta
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-riscv