Commit d34599bc authored by Lad Prabhakar's avatar Lad Prabhakar Committed by Palmer Dabbelt

cache: Add L2 cache management for Andes AX45MP RISC-V core

I/O Coherence Port (IOCP) provides an AXI interface for connecting
external non-caching masters, such as DMA controllers. The accesses
from IOCP are coherent with D-Caches and L2 Cache.

IOCP is a specification option and is disabled on the Renesas RZ/Five
SoC due to this reason IP blocks using DMA will fail.

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

More info about PMA (section 10.3):
Link: http://www.andestech.com/wp-content/uploads/AX45MP-1C-Rev.-5.0.0-Datasheet.pdf

As a workaround for SoCs with IOCP disabled CMO needs to be handled by
software. Firstly OpenSBI configures the memory region as
"Memory, Non-cacheable, Bufferable" and passes this region as a global
shared dma pool as a DT node. With DMA_GLOBAL_POOL enabled all DMA
allocations happen from this region and synchronization callbacks are
implemented to synchronize when doing DMA transactions.

Example PMA region passes as a DT node from OpenSBI:
    reserved-memory {
        #address-cells = <2>;
        #size-cells = <2>;
        ranges;

        pma_resv0@58000000 {
            compatible = "shared-dma-pool";
            reg = <0x0 0x58000000 0x0 0x08000000>;
            no-map;
            linux,dma-default;
        };
    };
Signed-off-by: default avatarLad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: default avatarConor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com> # tyre-kicking on a d1
Link: https://lore.kernel.org/r/20230818135723.80612-6-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 3e7bf468
......@@ -20241,6 +20241,13 @@ S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
F: drivers/staging/
STANDALONE CACHE CONTROLLER DRIVERS
M: Conor Dooley <conor@kernel.org>
L: linux-riscv@lists.infradead.org
S: Maintained
T: git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/
F: drivers/cache
STARFIRE/DURALAN NETWORK DRIVER
M: Ion Badulescu <ionut@badula.org>
S: Odd Fixes
......
......@@ -15,6 +15,8 @@ source "drivers/base/Kconfig"
source "drivers/bus/Kconfig"
source "drivers/cache/Kconfig"
source "drivers/connector/Kconfig"
source "drivers/firmware/Kconfig"
......
......@@ -11,6 +11,7 @@ ifdef building_out_of_srctree
MAKEFLAGS += --include-dir=$(srctree)
endif
obj-y += cache/
obj-y += irqchip/
obj-y += bus/
......
# SPDX-License-Identifier: GPL-2.0
menu "Cache Drivers"
config AX45MP_L2_CACHE
bool "Andes Technology AX45MP L2 Cache controller"
depends on RISCV_DMA_NONCOHERENT
select RISCV_NONSTANDARD_CACHE_OPS
help
Support for the L2 cache controller on Andes Technology AX45MP platforms.
endmenu
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_AX45MP_L2_CACHE) += ax45mp_cache.o
// SPDX-License-Identifier: GPL-2.0
/*
* non-coherent cache functions for Andes AX45MP
*
* Copyright (C) 2023 Renesas Electronics Corp.
*/
#include <linux/cacheflush.h>
#include <linux/cacheinfo.h>
#include <linux/dma-direction.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <asm/dma-noncoherent.h>
/* L2 cache registers */
#define AX45MP_L2C_REG_CTL_OFFSET 0x8
#define AX45MP_L2C_REG_C0_CMD_OFFSET 0x40
#define AX45MP_L2C_REG_C0_ACC_OFFSET 0x48
#define AX45MP_L2C_REG_STATUS_OFFSET 0x80
/* D-cache operation */
#define AX45MP_CCTL_L1D_VA_INVAL 0 /* Invalidate an L1 cache entry */
#define AX45MP_CCTL_L1D_VA_WB 1 /* Write-back an L1 cache entry */
/* L2 CCTL status */
#define AX45MP_CCTL_L2_STATUS_IDLE 0
/* L2 CCTL status cores mask */
#define AX45MP_CCTL_L2_STATUS_C0_MASK 0xf
/* L2 cache operation */
#define AX45MP_CCTL_L2_PA_INVAL 0x8 /* Invalidate an L2 cache entry */
#define AX45MP_CCTL_L2_PA_WB 0x9 /* Write-back an L2 cache entry */
#define AX45MP_L2C_REG_PER_CORE_OFFSET 0x10
#define AX45MP_CCTL_L2_STATUS_PER_CORE_OFFSET 4
#define AX45MP_L2C_REG_CN_CMD_OFFSET(n) \
(AX45MP_L2C_REG_C0_CMD_OFFSET + ((n) * AX45MP_L2C_REG_PER_CORE_OFFSET))
#define AX45MP_L2C_REG_CN_ACC_OFFSET(n) \
(AX45MP_L2C_REG_C0_ACC_OFFSET + ((n) * AX45MP_L2C_REG_PER_CORE_OFFSET))
#define AX45MP_CCTL_L2_STATUS_CN_MASK(n) \
(AX45MP_CCTL_L2_STATUS_C0_MASK << ((n) * AX45MP_CCTL_L2_STATUS_PER_CORE_OFFSET))
#define AX45MP_CCTL_REG_UCCTLBEGINADDR_NUM 0x80b
#define AX45MP_CCTL_REG_UCCTLCOMMAND_NUM 0x80c
#define AX45MP_CACHE_LINE_SIZE 64
struct ax45mp_priv {
void __iomem *l2c_base;
u32 ax45mp_cache_line_size;
};
static struct ax45mp_priv ax45mp_priv;
/* L2 Cache operations */
static inline uint32_t ax45mp_cpu_l2c_get_cctl_status(void)
{
return readl(ax45mp_priv.l2c_base + AX45MP_L2C_REG_STATUS_OFFSET);
}
static void ax45mp_cpu_cache_operation(unsigned long start, unsigned long end,
unsigned int l1_op, unsigned int l2_op)
{
unsigned long line_size = ax45mp_priv.ax45mp_cache_line_size;
void __iomem *base = ax45mp_priv.l2c_base;
int mhartid = smp_processor_id();
unsigned long pa;
while (end > start) {
csr_write(AX45MP_CCTL_REG_UCCTLBEGINADDR_NUM, start);
csr_write(AX45MP_CCTL_REG_UCCTLCOMMAND_NUM, l1_op);
pa = virt_to_phys((void *)start);
writel(pa, base + AX45MP_L2C_REG_CN_ACC_OFFSET(mhartid));
writel(l2_op, 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;
}
}
/* Write-back L1 and L2 cache entry */
static inline void ax45mp_cpu_dcache_wb_range(unsigned long start, unsigned long end)
{
ax45mp_cpu_cache_operation(start, end, AX45MP_CCTL_L1D_VA_WB,
AX45MP_CCTL_L2_PA_WB);
}
/* Invalidate the L1 and L2 cache entry */
static inline void ax45mp_cpu_dcache_inval_range(unsigned long start, unsigned long end)
{
ax45mp_cpu_cache_operation(start, end, AX45MP_CCTL_L1D_VA_INVAL,
AX45MP_CCTL_L2_PA_INVAL);
}
static void ax45mp_dma_cache_inv(phys_addr_t paddr, size_t size)
{
unsigned long start = (unsigned long)phys_to_virt(paddr);
unsigned long end = start + size;
unsigned long line_size;
unsigned long flags;
if (unlikely(start == end))
return;
line_size = ax45mp_priv.ax45mp_cache_line_size;
start = start & (~(line_size - 1));
end = ((end + line_size - 1) & (~(line_size - 1)));
local_irq_save(flags);
ax45mp_cpu_dcache_inval_range(start, end);
local_irq_restore(flags);
}
static void ax45mp_dma_cache_wback(phys_addr_t paddr, size_t size)
{
unsigned long start = (unsigned long)phys_to_virt(paddr);
unsigned long end = start + size;
unsigned long line_size;
unsigned long flags;
line_size = ax45mp_priv.ax45mp_cache_line_size;
start = start & (~(line_size - 1));
local_irq_save(flags);
ax45mp_cpu_dcache_wb_range(start, end);
local_irq_restore(flags);
}
static void ax45mp_dma_cache_wback_inv(phys_addr_t paddr, size_t size)
{
ax45mp_dma_cache_wback(paddr, size);
ax45mp_dma_cache_inv(paddr, size);
}
static int ax45mp_get_l2_line_size(struct device_node *np)
{
int ret;
ret = of_property_read_u32(np, "cache-line-size", &ax45mp_priv.ax45mp_cache_line_size);
if (ret) {
pr_err("Failed to get cache-line-size, defaulting to 64 bytes\n");
return ret;
}
if (ax45mp_priv.ax45mp_cache_line_size != AX45MP_CACHE_LINE_SIZE) {
pr_err("Expected cache-line-size to be 64 bytes (found:%u)\n",
ax45mp_priv.ax45mp_cache_line_size);
return -EINVAL;
}
return 0;
}
static const struct riscv_nonstd_cache_ops ax45mp_cmo_ops __initdata = {
.wback = &ax45mp_dma_cache_wback,
.inv = &ax45mp_dma_cache_inv,
.wback_inv = &ax45mp_dma_cache_wback_inv,
};
static const struct of_device_id ax45mp_cache_ids[] = {
{ .compatible = "andestech,ax45mp-cache" },
{ /* sentinel */ }
};
static int __init ax45mp_cache_init(void)
{
struct device_node *np;
struct resource res;
int ret;
np = of_find_matching_node(NULL, ax45mp_cache_ids);
if (!of_device_is_available(np))
return -ENODEV;
ret = of_address_to_resource(np, 0, &res);
if (ret)
return ret;
/*
* If IOCP is present on the Andes AX45MP core riscv_cbom_block_size
* will be 0 for sure, so we can definitely rely on it. If
* riscv_cbom_block_size = 0 we don't need to handle CMO using SW any
* more so we just return success here and only if its being set we
* continue further in the probe path.
*/
if (!riscv_cbom_block_size)
return 0;
ax45mp_priv.l2c_base = ioremap(res.start, resource_size(&res));
if (!ax45mp_priv.l2c_base)
return -ENOMEM;
ret = ax45mp_get_l2_line_size(np);
if (ret) {
iounmap(ax45mp_priv.l2c_base);
return ret;
}
riscv_noncoherent_register_cache_ops(&ax45mp_cmo_ops);
return 0;
}
early_initcall(ax45mp_cache_init);
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