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Date: Wed, 26 Oct 2022 00:07:50 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Magnus Damm <magnus.damm@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Heiko Stuebner <heiko@...ech.de>,
Conor Dooley <conor.dooley@...rochip.com>,
Guo Ren <guoren@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Nathan Chancellor <nathan@...nel.org>,
Atish Patra <atishp@...osinc.com>,
Anup Patel <anup@...infault.org>,
Andrew Jones <ajones@...tanamicro.com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org, linux-renesas-soc@...r.kernel.org,
Biju Das <biju.das.jz@...renesas.com>,
Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [RFC PATCH v3 2/2] soc: renesas: Add L2 cache management for
RZ/Five SoC
Hi Geert,
Thank you for the review.
On Mon, Oct 24, 2022 at 3:22 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> (fixed Palmer's address)
>
> On Thu, Oct 20, 2022 at 12:02 AM Prabhakar <prabhakar.csengg@...il.com> wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > On the AX45MP core, cache coherency is a specification option so it may
> > not be supported. In this case DMA will fail. As a workaround, firstly we
> > allocate a global dma coherent pool from which DMA allocations are taken
> > and marked as non-cacheable + bufferable using the PMA region as specified
> > in the device tree. Synchronization callbacks are implemented to
> > synchronize when doing DMA transactions.
> >
> > The Andes AX45MP core has a Programmable Physical Memory Attributes (PMA)
> > block that allows dynamic adjustment of memory attributes in the runtime.
> > It contains a configurable amount of PMA entries implemented as CSR
> > registers to control the attributes of memory locations in interest.
> >
> > Below are the memory attributes supported:
> > * Device, Non-bufferable
> > * Device, bufferable
> > * Memory, Non-cacheable, Non-bufferable
> > * Memory, Non-cacheable, Bufferable
> > * Memory, Write-back, No-allocate
> > * Memory, Write-back, Read-allocate
> > * Memory, Write-back, Write-allocate
> > * Memory, Write-back, Read and Write-allocate
> >
> > This patch adds support to configure the memory attributes of the memory
> > regions as passed from the l2 cache node and exposes the cache management
> > ops.
> >
> > More info about PMA (section 10.3):
> > http://www.andestech.com/wp-content/uploads/AX45MP-1C-Rev.-5.0.0-Datasheet.pdf
> >
> > This feature is based on the work posted [0] by Vincent Chen
> > <vincentc@...estech.com> for the Andes AndeStart RISC-V CPU.
> >
> > [0] https://lore.kernel.org/lkml/1540982130-28248-1-git-send-email-vincentc@andestech.com/
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Thanks for your patch!
>
> > --- a/drivers/soc/renesas/Kconfig
> > +++ b/drivers/soc/renesas/Kconfig
> > @@ -340,9 +340,14 @@ if RISCV
> > config ARCH_R9A07G043
> > bool "RISC-V Platform support for RZ/Five"
> > select ARCH_RZG2L
> > + select AX45MP_L2_CACHE
> > + select DMA_GLOBAL_POOL
> > + select RISCV_DMA_NONCOHERENT
> > help
> > This enables support for the Renesas RZ/Five SoC.
> >
> > +source "drivers/soc/renesas/rzf/Kconfig"
>
> s/rzf/rzfive/? (or "rz5"? "rzv"?)
>
OK, I'll rename it to rzfive instead.
> > +
> > endif # RISCV
> >
> > config RST_RCAR
> > diff --git a/drivers/soc/renesas/Makefile b/drivers/soc/renesas/Makefile
> > index 535868c9c7e4..a20cc7ad5b12 100644
> > --- a/drivers/soc/renesas/Makefile
> > +++ b/drivers/soc/renesas/Makefile
> > @@ -31,6 +31,10 @@ ifdef CONFIG_SMP
> > obj-$(CONFIG_ARCH_R9A06G032) += r9a06g032-smp.o
> > endif
> >
> > +ifdef CONFIG_RISCV
> > +obj-y += rzf/
> > +endif
>
> obj-$(CONFIG_RISCV)
>
Agreed.
> > --- /dev/null
> > +++ b/drivers/soc/renesas/rzf/Kconfig
> > @@ -0,0 +1,6 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +config AX45MP_L2_CACHE
> > + bool "AX45MP L2 Cache controller"
>
> Andes Technology ...
>
OK, "Andes Technology AX45MP L2 Cache controller"
> > + help
> > + Support for the L2 cache controller on AX45MP platforms.
>
> ... Andes Technology ...
>
OK.
> > --- /dev/null
> > +++ b/drivers/soc/renesas/rzf/ax45mp_cache.c
> > @@ -0,0 +1,431 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * PMA setup and non-coherent cache functions for AX45MP
> > + *
> > + * Copyright (C) 2022 Renesas Electronics Corp.
> > + */
> > +
> > +#include <linux/cacheflush.h>
> > +#include <linux/cacheinfo.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_platform.h>
> > +
> > +#include <asm/sbi.h>
> > +
> > +#include "ax45mp_sbi.h"
> > +
> > +/* L2 cache registers */
> > +#define AX45MP_L2C_REG_CTL_OFFSET 0x8
> > +#define AX45MP_L2C_IPREPETCH_OFF 3
> > +#define AX45MP_L2C_DPREPETCH_OFF 5
> > +#define AX45MP_L2C_IPREPETCH_MSK (3 << AX45MP_L2C_IPREPETCH_OFF)
> > +#define AX45MP_L2C_DPREPETCH_MSK (3 << AX45MP_L2C_DPREPETCH_OFF)
>
> #define AX45MP_L2C_IPREPETCH GENMASK(4, 3)
> etc., and then you can use the FIELD_PREP() macros.
>
Agreed, now that we have decided to drop the setup of l2c controls the
above macros can be dropped.
> > +#define AX45MP_L2C_TRAMOCTL_OFF 8
> > +#define AX45MP_L2C_TRAMICTL_OFF 10
> > +#define AX45MP_L2C_TRAMOCTL_MSK (3 << AX45MP_L2C_TRAMOCTL_OFF)
> > +#define AX45MP_L2C_TRAMICTL_MSK BIT(AX45MP_L2C_TRAMICTL_OFF)
> > +#define AX45MP_L2C_DRAMOCTL_OFF 11
> > +#define AX45MP_L2C_DRAMICTL_OFF 13
> > +#define AX45MP_L2C_DRAMOCTL_MSK (3 << AX45MP_L2C_DRAMOCTL_OFF)
> > +#define AX45MP_L2C_DRAMICTL_MSK BIT(AX45MP_L2C_DRAMICTL_OFF)
>
> > +
> > +#define AX45MP_MAX_CACHE_LINE_SIZE 256
> > +
> > +#define AX45MP_MAX_PMA_REGIONS 16
> > +
> > +struct ax45mp_priv {
> > + void __iomem *l2c_base;
> > + unsigned int ax45mp_cache_line_size;
> > + bool l2cache_enabled;
> > + bool ucctl_ok;
> > +};
> > +
> > +static struct ax45mp_priv *ax45mp_priv;
> > +static DEFINE_STATIC_KEY_FALSE(ax45mp_l2c_configured);
> > +
> > +/* PMA setup */
> > +static long ax45mp_sbi_set_pma(unsigned long start,
> > + unsigned long size,
> > + unsigned long flags,
> > + unsigned int entry_id)
> > +{
> > + struct sbiret ret;
> > +
> > + ret = sbi_ecall(SBI_EXT_ANDES, AX45MP_SBI_EXT_SET_PMA,
> > + start, start + size, size, entry_id,
> > + flags, 0);
>
> Fits on two lines.
>
OK.
On a second look the "start + size" arg can be dropped as this can be
calculated in OpenSBI, so I'll fix it in OpenSBI and here too.
> > +
> > + return ret.value;
> > +}
> > +
> > +static int ax45mp_configure_pma_regions(struct device_node *np)
> > +{
> > + const char *propname = "andestech,pma-regions";
> > + u64 start, size, flags;
> > + unsigned int entry_id;
> > + unsigned int i;
> > + int count;
> > + int ret;
> > +
> > + count = of_property_count_elems_of_size(np, propname,
> > + sizeof(u32) * 6);
>
> Fits on a single line.
>
OK.
> > +static inline uint32_t ax45mp_cpu_l2c_get_cctl_status(void)
> > +{
> > + return readl((void *)(ax45mp_priv->l2c_base + AX45MP_L2C_REG_STATUS_OFFSET));
>
> Why the cast to "(void *)"?
>
Can be dropped.
> > +}
> > +
> > +static inline uint32_t ax45mp_cpu_l2c_ctl_status(void)
> > +{
> > + return readl((void *)(ax45mp_priv->l2c_base + AX45MP_L2C_REG_CTL_OFFSET));
>
> Likewise.
>
Ditto.
> > +}
>
> > +static void ax45mp_cpu_dcache_wb_range(unsigned long start,
> > + unsigned long end,
> > + int line_size)
> > +{
> > + void __iomem *base = ax45mp_priv->l2c_base;
> > + unsigned long pa;
> > + int mhartid = 0;
> > +#ifdef CONFIG_SMP
> > + mhartid = smp_processor_id();
> > +#endif
> > +
> > + while (end > start) {
> > + if (ax45mp_priv->ucctl_ok) {
> > + csr_write(AX45MP_CCTL_REG_UCCTLBEGINADDR_NUM, start);
> > + csr_write(AX45MP_CCTL_REG_UCCTLCOMMAND_NUM, AX45MP_CCTL_L1D_VA_WB);
> > + }
> > +
> > + if (ax45mp_priv->l2cache_enabled) {
> > + pa = virt_to_phys((void *)start);
>
> Looks like start and end should be "void *" instead of " unsigned long",
> as they are virtual addresses. See also below...
>
OK.
> > + writel(pa, (void *)(base + AX45MP_L2C_REG_CN_ACC_OFFSET(mhartid)));
> > + writel(AX45MP_CCTL_L2_PA_WB,
> > + (void *)(base + AX45MP_L2C_REG_CN_CMD_OFFSET(mhartid)));
>
> Why the casts to "(void *)"?
>
Can be dropped.
> > + while ((ax45mp_cpu_l2c_get_cctl_status() &
> > + AX45MP_CCTL_L2_STATUS_CN_MASK(mhartid)) !=
> > + AX45MP_CCTL_L2_STATUS_IDLE)
> > + ;
> > + }
> > +
> > + start += line_size;
> > + }
> > +}
> > +
> > +static void ax45mp_cpu_dcache_inval_range(unsigned long start,
> > + unsigned long end,
> > + int line_size)
> > +{
> > + void __iomem *base = ax45mp_priv->l2c_base;
> > + unsigned long pa;
> > + int mhartid = 0;
> > +#ifdef CONFIG_SMP
> > + mhartid = smp_processor_id();
> > +#endif
> > +
> > + while (end > start) {
> > + if (ax45mp_priv->ucctl_ok) {
> > + csr_write(AX45MP_CCTL_REG_UCCTLBEGINADDR_NUM, start);
> > + csr_write(AX45MP_CCTL_REG_UCCTLCOMMAND_NUM, AX45MP_CCTL_L1D_VA_INVAL);
> > + }
> > +
> > + if (ax45mp_priv->l2cache_enabled) {
> > + pa = virt_to_phys((void *)start);
>
> Looks like start and end should be "void *" instead of " unsigned long",
> as they are virtual addresses. See also below...
>
OK.
> > + writel(pa, (void *)(base + AX45MP_L2C_REG_CN_ACC_OFFSET(mhartid)));
> > + writel(AX45MP_CCTL_L2_PA_INVAL,
> > + (void *)(base + AX45MP_L2C_REG_CN_CMD_OFFSET(mhartid)));
> > + while ((ax45mp_cpu_l2c_get_cctl_status() &
> > + AX45MP_CCTL_L2_STATUS_CN_MASK(mhartid)) !=
> > + AX45MP_CCTL_L2_STATUS_IDLE)
> > + ;
> > + }
> > +
> > + start += line_size;
> > + }
> > +}
> > +
> > +void ax45mp_cpu_dma_inval_range(void *vaddr, size_t size)
> > +{
> > + char cache_buf[2][AX45MP_MAX_CACHE_LINE_SIZE] = { 0 };
>
> AX45MP_MAX_CACHE_LINE_SIZE = 256, so 512 bytes of data on the stack,
> auto-initialized by memset().
>
> Please remove the { 0 }, ...
>
Ok will do.
> > + unsigned long start = (unsigned long)vaddr;
> > + unsigned long end = start + size;
> > + unsigned long old_start = start;
> > + unsigned long old_end = end;
> > + unsigned long line_size;
> > + unsigned long flags;
> > +
> > + if (static_branch_unlikely(&ax45mp_l2c_configured) && !ax45mp_priv)
> > + return;
> > +
> > + if (unlikely(start == end))
> > + return;
> > +
> > + line_size = ax45mp_priv->ax45mp_cache_line_size;
>
> ... and call memset() here, so the buffer is not initialized when unused.
> Perhaps use two buffers, so you can easily memset() only the part that is
> used?
>
OK.
> > +
> > + start = start & (~(line_size - 1));
> > + end = ((end + line_size - 1) & (~(line_size - 1)));
>
> These are the only calculations that need to use "unsigned long"
> instead of "void *", but you can use PTR_ALIGN_DOWN() and PTR_ALIGN()
> to avoid explicit casts.
>
Good point.
> > +
> > + local_irq_save(flags);
> > + if (unlikely(start != old_start))
> > + memcpy(&cache_buf[0][0], (void *)start, line_size);
> > +
> > + if (unlikely(end != old_end))
> > + memcpy(&cache_buf[1][0], (void *)(old_end & (~(line_size - 1))), line_size);
>
> PTR_ALIGN_DOWN()
>
OK.
> > +
> > + ax45mp_cpu_dcache_inval_range(start, end, line_size);
> > +
> > + if (unlikely(start != old_start))
> > + memcpy((void *)start, &cache_buf[0][0], (old_start & (line_size - 1)));
> > +
> > + if (unlikely(end != old_end))
> > + memcpy((void *)(old_end + 1),
> > + &cache_buf[1][(old_end & (line_size - 1)) + 1],
> > + end - old_end - 1);
> > +
> > + local_irq_restore(flags);
> > +}
> > +EXPORT_SYMBOL(ax45mp_cpu_dma_inval_range);
> > +
> > +void ax45mp_cpu_dma_wb_range(void *vaddr, size_t size)
> > +{
> > + unsigned long start = (unsigned long)vaddr;
> > + unsigned long end = start + size;
> > + unsigned long line_size;
> > + unsigned long flags;
> > +
> > + if (static_branch_unlikely(&ax45mp_l2c_configured) && !ax45mp_priv)
> > + return;
> > +
> > + line_size = ax45mp_priv->ax45mp_cache_line_size;
> > + local_irq_save(flags);
> > + start = start & (~(line_size - 1));
>
> PTR_ALIGN_DOWN() etc...
>
OK.
> > + ax45mp_cpu_dcache_wb_range(start, end, line_size);
> > + local_irq_restore(flags);
> > +}
> > +EXPORT_SYMBOL(ax45mp_cpu_dma_wb_range);
> > +
> > +static int ax45mp_configure_l2_cache(struct device_node *np)
> > +{
> > + u8 ram_ctl[2];
> > + u32 cache_ctl;
> > + u32 prefetch;
> > + int ret;
> > +
> > + cache_ctl = ax45mp_cpu_l2c_ctl_status();
> > +
> > + /* Instruction and data fetch prefetch depth */
> > + ret = of_property_read_u32(np, "andestech,inst-prefetch", &prefetch);
> > + if (!ret) {
> > + cache_ctl &= ~AX45MP_L2C_IPREPETCH_MSK;
> > + cache_ctl |= (prefetch << AX45MP_L2C_IPREPETCH_OFF);
>
> FIELD_PREP(), also below
>
This entire function will be dropped now...
> > + }
> > +
> > + ret = of_property_read_u32(np, "andestech,data-prefetch", &prefetch);
> > + if (!ret) {
> > + cache_ctl &= ~AX45MP_L2C_DPREPETCH_MSK;
> > + cache_ctl |= (prefetch << AX45MP_L2C_DPREPETCH_OFF);
>
> prefect / 2
>
> > + }
> > +
> > + /* tag RAM and data RAM setup and output cycle */
> > + ret = of_property_read_u8_array(np, "andestech,tag-ram-ctl", ram_ctl, 2);
> > + if (!ret) {
> > + cache_ctl &= ~(AX45MP_L2C_TRAMOCTL_MSK | AX45MP_L2C_TRAMICTL_MSK);
> > + cache_ctl |= ram_ctl[0] << AX45MP_L2C_TRAMOCTL_OFF;
> > + cache_ctl |= ram_ctl[1] << AX45MP_L2C_TRAMICTL_OFF;
> > + }
> > +
> > + ret = of_property_read_u8_array(np, "andestech,data-ram-ctl", ram_ctl, 2);
> > + if (!ret) {
> > + cache_ctl &= ~(AX45MP_L2C_DRAMOCTL_MSK | AX45MP_L2C_DRAMICTL_MSK);
> > + cache_ctl |= ram_ctl[0] << AX45MP_L2C_DRAMOCTL_OFF;
> > + cache_ctl |= ram_ctl[1] << AX45MP_L2C_DRAMICTL_OFF;
> > + }
> > +
> > + writel(cache_ctl, ax45mp_priv->l2c_base + AX45MP_L2C_REG_CTL_OFFSET);
> > +
> > + ret = of_property_read_u32(np, "cache-line-size", &ax45mp_priv->ax45mp_cache_line_size);
>
> According to the bindings, this must be 64?
>
Agreed, I'll add a check to make sure it's always 64.
Cheers,
Prabhakar
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