Re: [PATCH v4 7/7] soc: renesas: Add L2 cache management for RZ/Five SoC

[Samuel Holland]

Hi Prabhakar,

On 11/24/22 11:22, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> 
> 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.

Forgive my ignorance, but why do you need both a DMA pool and explicit
cache maintenance? Wouldn't the purpose of marking a memory region as
permanently non-cacheable be to avoid cache maintenance? And likewise,
if you are doing cache maintenance anyway, why does it matter if/how the
memory is cacheable?

> More info about PMA (section 10.3):
> Link: http://www.andestech.com/wp-content/uploads/AX45MP-1C-Rev.-5.0.0-Datasheet.pdf
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> ---
> RFC v3 -> v4
> * Made use of runtime patching instead of compile time
> * Now just exposing single function ax45mp_no_iocp_cmo() for CMO handling
> * Added a check to make sure cache line size is always 64 bytes
> * Renamed folder rzf -> rzfive
> * Improved Kconfig description
> * Dropped L2 cache configuration
> * Dropped unnecessary casts
> * Fixed comments pointed by Geert, apart from use of PTR_ALIGN_XYZ() macros.
> ---
>  arch/riscv/include/asm/cacheflush.h       |   8 +
>  arch/riscv/include/asm/errata_list.h      |  32 +-
>  drivers/soc/renesas/Kconfig               |   7 +
>  drivers/soc/renesas/Makefile              |   2 +
>  drivers/soc/renesas/rzfive/Kconfig        |   6 +
>  drivers/soc/renesas/rzfive/Makefile       |   3 +
>  drivers/soc/renesas/rzfive/ax45mp_cache.c | 415 ++++++++++++++++++++++
>  drivers/soc/renesas/rzfive/ax45mp_sbi.h   |  29 ++
>  8 files changed, 496 insertions(+), 6 deletions(-)
>  create mode 100644 drivers/soc/renesas/rzfive/Kconfig
>  create mode 100644 drivers/soc/renesas/rzfive/Makefile
>  create mode 100644 drivers/soc/renesas/rzfive/ax45mp_cache.c
>  create mode 100644 drivers/soc/renesas/rzfive/ax45mp_sbi.h
> 
> diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
> index 4a04d1be7c67..3226f3aceafe 100644
> --- a/arch/riscv/include/asm/cacheflush.h
> +++ b/arch/riscv/include/asm/cacheflush.h
> @@ -61,6 +61,14 @@ static inline void riscv_noncoherent_supported(void) {}
>  #define SYS_RISCV_FLUSH_ICACHE_LOCAL 1UL
>  #define SYS_RISCV_FLUSH_ICACHE_ALL   (SYS_RISCV_FLUSH_ICACHE_LOCAL)
>  
> +#ifdef CONFIG_AX45MP_L2_CACHE
> +extern asmlinkage void ax45mp_no_iocp_cmo(unsigned int cache_size, void *vaddr,
> +					  size_t size, int dir, int ops);
> +#else
> +inline void ax45mp_no_iocp_cmo(unsigned int cache_size, void *vaddr,
> +			       size_t size, int dir, int ops) {}
> +#endif
> +
>  #include <asm-generic/cacheflush.h>
>  
>  #endif /* _ASM_RISCV_CACHEFLUSH_H */
> diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
> index 48e899a8e7a9..300fed3bfd80 100644
> --- a/arch/riscv/include/asm/errata_list.h
> +++ b/arch/riscv/include/asm/errata_list.h
> @@ -125,8 +125,8 @@ asm volatile(ALTERNATIVE(						\
>  #define THEAD_SYNC_S	".long 0x0190000b"
>  
>  #define ALT_CMO_OP(_op, _start, _size, _cachesize, _dir, _ops)		\
> -asm volatile(ALTERNATIVE_2(						\
> -	__nops(6),							\
> +asm volatile(ALTERNATIVE_3(						\
> +	__nops(14),							\
>  	"mv a0, %1\n\t"							\
>  	"j 2f\n\t"							\
>  	"3:\n\t"							\
> @@ -134,7 +134,7 @@ asm volatile(ALTERNATIVE_2(						\
>  	"add a0, a0, %0\n\t"						\
>  	"2:\n\t"							\
>  	"bltu a0, %2, 3b\n\t"						\
> -	"nop", 0, CPUFEATURE_ZICBOM, CONFIG_RISCV_ISA_ZICBOM,		\
> +	__nops(8), 0, CPUFEATURE_ZICBOM, CONFIG_RISCV_ISA_ZICBOM,	\
>  	"mv a0, %1\n\t"							\
>  	"j 2f\n\t"							\
>  	"3:\n\t"							\
> @@ -142,8 +142,28 @@ asm volatile(ALTERNATIVE_2(						\
>  	"add a0, a0, %0\n\t"						\
>  	"2:\n\t"							\
>  	"bltu a0, %2, 3b\n\t"						\
> -	THEAD_SYNC_S, THEAD_VENDOR_ID,					\
> -			ERRATA_THEAD_CMO, CONFIG_ERRATA_THEAD_CMO)	\
> +	THEAD_SYNC_S "\n\t"						\
> +	__nops(8), THEAD_VENDOR_ID,					\
> +			ERRATA_THEAD_CMO, CONFIG_ERRATA_THEAD_CMO,	\
> +	".option push\n\t\n\t"						\
> +	".option norvc\n\t"						\
> +	".option norelax\n\t"						\
> +	"addi sp,sp,-16\n\t"						\
> +	"sd s0,0(sp)\n\t"						\
> +	"sd ra,8(sp)\n\t"						\
> +	"addi s0,sp,16\n\t"						\
> +	"mv a4,%6\n\t"							\
> +	"mv a3,%5\n\t"							\
> +	"mv a2,%4\n\t"							\
> +	"mv a1,%3\n\t"							\
> +	"mv a0,%0\n\t"							\
> +	"call ax45mp_no_iocp_cmo\n\t"					\
> +	"ld ra,8(sp)\n\t"						\
> +	"ld s0,0(sp)\n\t"						\
> +	"addi sp,sp,16\n\t"						\
> +	".option pop\n\t",						\
> +	ANDESTECH_VENDOR_ID, ERRATA_ANDESTECH_NO_IOCP,			\
> +	CONFIG_ERRATA_ANDES_CMO)					\
>  	: : "r"(_cachesize),						\
>  	    "r"((unsigned long)(_start) & ~((_cachesize) - 1UL)),	\
>  	    "r"((unsigned long)(_start) + (_size)),			\
> @@ -151,7 +171,7 @@ asm volatile(ALTERNATIVE_2(						\
>  	    "r"((unsigned long)(_size)),				\
>  	    "r"((unsigned long)(_dir)),					\
>  	    "r"((unsigned long)(_ops))					\
> -	: "a0")
> +	: "a0", "a1", "a2", "a3", "a4", "memory")
>  
>  #define THEAD_C9XX_RV_IRQ_PMU			17
>  #define THEAD_C9XX_CSR_SCOUNTEROF		0x5c5
> diff --git a/drivers/soc/renesas/Kconfig b/drivers/soc/renesas/Kconfig
> index 660498252ec5..e7810256c60d 100644
> --- a/drivers/soc/renesas/Kconfig
> +++ b/drivers/soc/renesas/Kconfig
> @@ -340,9 +340,16 @@ 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 ERRATA_ANDES
> +	select ERRATA_ANDES_CMO
> +	select RISCV_DMA_NONCOHERENT
>  	help
>  	  This enables support for the Renesas RZ/Five SoC.
>  
> +source "drivers/soc/renesas/rzfive/Kconfig"
> +
>  endif # RISCV
>  
>  config RST_RCAR
> diff --git a/drivers/soc/renesas/Makefile b/drivers/soc/renesas/Makefile
> index 535868c9c7e4..9df9f759a039 100644
> --- a/drivers/soc/renesas/Makefile
> +++ b/drivers/soc/renesas/Makefile
> @@ -31,6 +31,8 @@ ifdef CONFIG_SMP
>  obj-$(CONFIG_ARCH_R9A06G032)	+= r9a06g032-smp.o
>  endif
>  
> +obj-$(CONFIG_RISCV) += rzfive/
> +
>  # Family
>  obj-$(CONFIG_RST_RCAR)		+= rcar-rst.o
>  obj-$(CONFIG_SYSC_RCAR)		+= rcar-sysc.o
> diff --git a/drivers/soc/renesas/rzfive/Kconfig b/drivers/soc/renesas/rzfive/Kconfig
> new file mode 100644
> index 000000000000..b6bc00337d99
> --- /dev/null
> +++ b/drivers/soc/renesas/rzfive/Kconfig
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +config AX45MP_L2_CACHE
> +	bool "Andes Technology AX45MP L2 Cache controller"
> +	help
> +	  Support for the L2 cache controller on Andes Technology AX45MP platforms.
> diff --git a/drivers/soc/renesas/rzfive/Makefile b/drivers/soc/renesas/rzfive/Makefile
> new file mode 100644
> index 000000000000..2012e7fb978d
> --- /dev/null
> +++ b/drivers/soc/renesas/rzfive/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_AX45MP_L2_CACHE) += ax45mp_cache.o
> diff --git a/drivers/soc/renesas/rzfive/ax45mp_cache.c b/drivers/soc/renesas/rzfive/ax45mp_cache.c
> new file mode 100644
> index 000000000000..4e0d0545d3af
> --- /dev/null
> +++ b/drivers/soc/renesas/rzfive/ax45mp_cache.c
> @@ -0,0 +1,415 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * PMA setup and non-coherent cache functions for Andes AX45MP
> + *
> + * Copyright (C) 2022 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/cacheflush.h>
> +#include <asm/sbi.h>
> +
> +#include "ax45mp_sbi.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
> +#define AX45MP_CCTL_L1D_VA_WB			1
> +
> +/* L2 cache */
> +#define AX45MP_L2_CACHE_CTL_CEN_MASK		1
> +
> +/* 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
> +#define AX45MP_CCTL_L2_PA_WB			0x9
> +
> +#define AX45MP_L2C_HPM_PER_CORE_OFFSET		0x8
> +#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_MICM_CFG_ISZ_OFFSET		6
> +#define AX45MP_MICM_CFG_ISZ_MASK		(0x7  << AX45MP_MICM_CFG_ISZ_OFFSET)
> +
> +#define AX45MP_MDCM_CFG_DSZ_OFFSET		6
> +#define AX45MP_MDCM_CFG_DSZ_MASK		(0x7  << AX45MP_MDCM_CFG_DSZ_OFFSET)
> +
> +#define AX45MP_CCTL_REG_UCCTLBEGINADDR_NUM	0x80b
> +#define AX45MP_CCTL_REG_UCCTLCOMMAND_NUM	0x80c
> +
> +#define AX45MP_MCACHE_CTL_CCTL_SUEN_OFFSET	8
> +#define AX45MP_MMSC_CFG_CCTLCSR_OFFSET		16
> +#define AX45MP_MISA_20_OFFSET			20
> +
> +#define AX45MP_MCACHE_CTL_CCTL_SUEN_MASK	(0x1 << AX45MP_MCACHE_CTL_CCTL_SUEN_OFFSET)
> +#define AX45MP_MMSC_CFG_CCTLCSR_MASK		(0x1 << AX45MP_MMSC_CFG_CCTLCSR_OFFSET)
> +#define AX45MP_MISA_20_MASK			(0x1 << AX45MP_MISA_20_OFFSET)
> +
> +#define AX45MP_MAX_CACHE_LINE_SIZE		256
> +
> +#define AX45MP_MAX_PMA_REGIONS			16
> +
> +struct ax45mp_priv {
> +	void __iomem *l2c_base;
> +	u32 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, size, entry_id, flags, 0, 0);
> +
> +	return ret.value;
> +}
> +
> +static int ax45mp_configure_pma_regions(struct device_node *np)
> +{
> +	const char *propname = "andestech,pma-regions";
> +	u32 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) * 3);
> +	if (count < 0)
> +		return count;
> +
> +	if (count > AX45MP_MAX_PMA_REGIONS)
> +		return -EINVAL;
> +
> +	for (i = 0, entry_id = 0 ; entry_id < count ; i += 3, entry_id++) {
> +		of_property_read_u32_index(np, propname, i, &start);
> +		of_property_read_u32_index(np, propname, i + 1, &size);
> +		of_property_read_u32_index(np, propname, i + 2, &flags);
> +		ret = ax45mp_sbi_set_pma(start, size, flags, entry_id);
> +		if (!ret)
> +			pr_err("Failed to setup PMA region 0x%x - 0x%x flags: 0x%x",
> +			       start, start + size, flags);
> +	}
> +
> +	return 0;
> +}

If firmware support is required to set up these PMA regions, why is
Linux doing this at all? The firmware has access to the devicetree as
well. It can set this up before entering S-mode, and then you don't need
to expose this capability via an SBI extension. In fact, firmware could
generate the reserved-memory node based on these regions at runtime (or
vice versa).

> +
> +/* L2 Cache operations */
> +static uint32_t ax45mp_cpu_get_mcache_ctl_status(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_ANDES, AX45MP_SBI_EXT_GET_MCACHE_CTL_STATUS,
> +			0, 0, 0, 0, 0, 0);
> +	return ret.value;
> +}
> +
> +static uint32_t ax45mp_cpu_get_micm_cfg_status(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_ANDES, AX45MP_SBI_EXT_GET_MICM_CTL_STATUS,
> +			0, 0, 0, 0, 0, 0);
> +	return ret.value;
> +}
> +
> +static uint32_t ax45mp_cpu_get_mdcm_cfg_status(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_ANDES, AX45MP_SBI_EXT_GET_MDCM_CTL_STATUS,
> +			0, 0, 0, 0, 0, 0);
> +	return ret.value;
> +}
> +
> +static uint32_t ax45mp_cpu_get_mmsc_cfg_status(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_ANDES, AX45MP_SBI_EXT_GET_MMSC_CTL_STATUS,
> +			0, 0, 0, 0, 0, 0);
> +	return ret.value;
> +}
> +
> +static uint32_t ax45mp_cpu_get_misa_cfg_status(void)
> +{
> +	struct sbiret ret;
> +
> +	ret = sbi_ecall(SBI_EXT_ANDES, AX45MP_SBI_EXT_GET_MISA_CTL_STATUS,
> +			0, 0, 0, 0, 0, 0);
> +	return ret.value;
> +}
> +
> +static inline uint32_t ax45mp_cpu_l2c_get_cctl_status(void)
> +{
> +	return readl(ax45mp_priv->l2c_base + AX45MP_L2C_REG_STATUS_OFFSET);
> +}
> +
> +static inline uint32_t ax45mp_cpu_l2c_ctl_status(void)
> +{
> +	return readl(ax45mp_priv->l2c_base + AX45MP_L2C_REG_CTL_OFFSET);
> +}
> +
> +static bool ax45mp_cpu_cache_controlable(void)
> +{
> +	return (((ax45mp_cpu_get_micm_cfg_status() & AX45MP_MICM_CFG_ISZ_MASK) ||
> +		 (ax45mp_cpu_get_mdcm_cfg_status() & AX45MP_MDCM_CFG_DSZ_MASK)) &&
> +		(ax45mp_cpu_get_misa_cfg_status() & AX45MP_MISA_20_MASK) &&
> +		(ax45mp_cpu_get_mmsc_cfg_status() & AX45MP_MMSC_CFG_CCTLCSR_MASK) &&
> +		(ax45mp_cpu_get_mcache_ctl_status() & AX45MP_MCACHE_CTL_CCTL_SUEN_MASK));
> +}
> +
> +static void ax45mp_cpu_dcache_wb_range(void *start, void *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

This doesn't need an #ifdef. smp_processor_id() already returns zero
when SMP is disabled.

> +
> +	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(start);
> +			writel(pa, base + AX45MP_L2C_REG_CN_ACC_OFFSET(mhartid));
> +			writel(AX45MP_CCTL_L2_PA_WB,
> +			       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;
> +	}
> +}
> +
> +static void ax45mp_cpu_dcache_inval_range(void *start, void *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(start);
> +			writel(pa, base + AX45MP_L2C_REG_CN_ACC_OFFSET(mhartid));
> +			writel(AX45MP_CCTL_L2_PA_INVAL,
> +			       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;
> +	}
> +}
> +
> +static void ax45mp_cpu_dma_inval_range(void *vaddr, size_t size)
> +{
> +	char cache_buf[2][AX45MP_MAX_CACHE_LINE_SIZE];
> +	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;
> +
> +	memset(&cache_buf, 0x0, sizeof(cache_buf));
> +	start = start & (~(line_size - 1));
> +	end = ((end + line_size - 1) & (~(line_size - 1)));
> +
> +	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);

The memcpy dance is only required if ax45mp_cache_line_size is larger
than ARCH_DMA_MINALIGN. Is that actually the case in practice? If not,
you could verify this in the probe function, and remove this logic.

> +
> +	ax45mp_cpu_dcache_inval_range(vaddr, (void *)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);
> +}
> +
> +static 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));
> +	ax45mp_cpu_dcache_wb_range(vaddr, (void *)end, line_size);
> +	local_irq_restore(flags);
> +}
> +
> +void ax45mp_no_iocp_cmo(unsigned int cache_size, void *vaddr, size_t size, int dir, int ops)
> +{
> +	if (ops == NON_COHERENT_DMA_PREP)
> +		return;
> +
> +	if (ops == NON_COHERENT_SYNC_DMA_FOR_DEVICE) {
> +		switch (dir) {
> +		case DMA_FROM_DEVICE:
> +			ax45mp_cpu_dma_inval_range(vaddr, size);
> +			break;
> +		case DMA_TO_DEVICE:
> +		case DMA_BIDIRECTIONAL:
> +			ax45mp_cpu_dma_wb_range(vaddr, size);
> +			break;
> +		default:
> +			break;
> +		}
> +		return;
> +	}
> +
> +	/* op == NON_COHERENT_SYNC_DMA_FOR_CPU */
> +	if (dir == DMA_BIDIRECTIONAL || dir == DMA_FROM_DEVICE)
> +		ax45mp_cpu_dma_inval_range(vaddr, size);
> +}
> +EXPORT_SYMBOL(ax45mp_no_iocp_cmo);
> +
> +static int ax45mp_configure_l2_cache(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");
> +		ax45mp_priv->ax45mp_cache_line_size = SZ_64;
> +	}
> +
> +	if (ax45mp_priv->ax45mp_cache_line_size != SZ_64) {
> +		pr_err("Expected cache-line-size to 64 bytes (found:%u). Defaulting to 64 bytes\n",
> +		       ax45mp_priv->ax45mp_cache_line_size);
> +		ax45mp_priv->ax45mp_cache_line_size = SZ_64;
> +	}

Ah, so you already do this. And SZ_64 == ARCH_DMA_MINALIGN. So you do
not need the memcpy logic.

> +
> +	ax45mp_priv->ucctl_ok = ax45mp_cpu_cache_controlable();
> +	ax45mp_priv->l2cache_enabled = ax45mp_cpu_l2c_ctl_status() & AX45MP_L2_CACHE_CTL_CEN_MASK;
> +
> +	return 0;
> +}
> +
> +static int ax45mp_l2c_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	int ret;
> +
> +	ax45mp_priv = devm_kzalloc(&pdev->dev, sizeof(*ax45mp_priv), GFP_KERNEL);
> +	if (!ax45mp_priv)
> +		return -ENOMEM;
> +
> +	ax45mp_priv->l2c_base = devm_of_iomap(&pdev->dev, pdev->dev.of_node, 0, NULL);

devm_platform_ioremap_resource()

> +	if (!ax45mp_priv->l2c_base) {
> +		ret = -ENOMEM;
> +		goto l2c_err;
> +	}
> +
> +	ret = ax45mp_configure_l2_cache(np);
> +	if (ret)
> +		goto l2c_err;
> +
> +	ret = ax45mp_configure_pma_regions(np);
> +	if (ret)
> +		goto l2c_err;
> +
> +	static_branch_disable(&ax45mp_l2c_configured);

Instead of enabling this before the probe function, and disabling it
afterward, just enable it once here, in the success case. Then you can
drop the !ax45mp_priv check in the functions above.

And none of the functions would get called anyway if the alternative is
not applied. I suppose it's not possible to do some of this probe logic
in the alternative check function?

> +
> +	return 0;
> +
> +l2c_err:
> +	devm_kfree(&pdev->dev, ax45mp_priv);
> +	ax45mp_priv = NULL;

None of this cleanup is necessary.

Regards,
Samuel

> +	return ret;
> +}
> +
> +static const struct of_device_id ax45mp_cache_ids[] = {
> +	{ .compatible = "andestech,ax45mp-cache" },
> +	{ /* sentinel */ }
> +};
> +
> +static struct platform_driver ax45mp_l2c_driver = {
> +	.driver = {
> +		.name = "ax45mp-l2c",
> +		.of_match_table = ax45mp_cache_ids,
> +	},
> +	.probe = ax45mp_l2c_probe,
> +};
> +
> +static int __init ax45mp_cache_init(void)
> +{
> +	static_branch_enable(&ax45mp_l2c_configured);
> +	return platform_driver_register(&ax45mp_l2c_driver);
> +}
> +arch_initcall(ax45mp_cache_init);
> +
> +MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Andes AX45MP L2 cache driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/soc/renesas/rzfive/ax45mp_sbi.h b/drivers/soc/renesas/rzfive/ax45mp_sbi.h
> new file mode 100644
> index 000000000000..1604874954d0
> --- /dev/null
> +++ b/drivers/soc/renesas/rzfive/ax45mp_sbi.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +
> +#ifndef __AX45MP_SBI_H
> +#define __AX45MP_SBI_H
> +
> +#define SBI_EXT_ANDES		0x0900031E
> +
> +enum ax45mp_sbi_ext_fid {
> +	AX45MP_SBI_EXT_GET_MCACHE_CTL_STATUS = 0,
> +	AX45MP_SBI_EXT_GET_MMISC_CTL_STATUS,
> +	AX45MP_SBI_EXT_SET_MCACHE_CTL,
> +	AX45MP_SBI_EXT_SET_MMISC_CTL,
> +	AX45MP_SBI_EXT_ICACHE_OP,
> +	AX45MP_SBI_EXT_DCACHE_OP,
> +	AX45MP_SBI_EXT_L1CACHE_I_PREFETCH,
> +	AX45MP_SBI_EXT_L1CACHE_D_PREFETCH,
> +	AX45MP_SBI_EXT_NON_BLOCKING_LOAD_STORE,
> +	AX45MP_SBI_EXT_WRITE_AROUND,
> +	AX45MP_SBI_EXT_SET_PMA,
> +	AX45MP_SBI_EXT_FREE_PMA,
> +	AX45MP_SBI_EXT_PROBE_PMA,
> +	AX45MP_SBI_EXT_DCACHE_WBINVAL_ALL,
> +	AX45MP_SBI_EXT_GET_MICM_CTL_STATUS,
> +	AX45MP_SBI_EXT_GET_MDCM_CTL_STATUS,
> +	AX45MP_SBI_EXT_GET_MMSC_CTL_STATUS,
> +	AX45MP_SBI_EXT_GET_MISA_CTL_STATUS,
> +};
> +
> +#endif