diff mbox series

[v6,5/6] cache: Add L2 cache management for Andes AX45MP RISC-V core

Message ID 20230106185526.260163-6-prabhakar.mahadev-lad.rj@bp.renesas.com
State New
Headers show
Series RISC-V non-coherent function pointer based cache management operations + non-coherent DMA support for AX45MP | expand

Commit Message

Lad, Prabhakar Jan. 6, 2023, 6:55 p.m. UTC
From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

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: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
v5 -> v6
* Moved driver to cache folder
* Switched to new API for CMO

v4 -> v5
* Dropped code for configuring L2 cache
* Dropped code for configuring PMA
* Updated commit message
* Added comments
* Changed static branch enable/disable order

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.
---
 drivers/Kconfig              |   2 +
 drivers/Makefile             |   1 +
 drivers/cache/Kconfig        |  10 ++
 drivers/cache/Makefile       |   3 +
 drivers/cache/ax45mp_cache.c | 279 +++++++++++++++++++++++++++++++++++
 5 files changed, 295 insertions(+)
 create mode 100644 drivers/cache/Kconfig
 create mode 100644 drivers/cache/Makefile
 create mode 100644 drivers/cache/ax45mp_cache.c

Comments

Conor Dooley Jan. 7, 2023, 12:09 a.m. UTC | #1
On Fri, Jan 06, 2023 at 06:55:25PM +0000, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> 
> 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: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

> diff --git a/drivers/cache/ax45mp_cache.c b/drivers/cache/ax45mp_cache.c
> new file mode 100644
> index 000000000000..556e6875627c
> --- /dev/null
> +++ b/drivers/cache/ax45mp_cache.c
> @@ -0,0 +1,279 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * non-coherent cache functions for Andes AX45MP
> + *
> + * Copyright (C) 2022 Renesas Electronics Corp.
> + */
> +
> +#include <asm/dma-noncoherent.h>
> +#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>

You don't actually need this anymore, do you?

> +static int ax45mp_l2c_probe(struct platform_device *pdev)
> +{
> +	struct riscv_cache_ops ax45mp_cmo_ops;
> +
> +	/*
> +	 * riscv_cbom_block_size is set very much earlier so we can
> +	 * definitely rely on it and only if its being set we continue
> +	 * further in the probe path.
> +	 */
> +	if (!riscv_cbom_block_size)
> +		return 0;

Return 0? That's because we may actually have the IOCP & do not want to
install ops, right?
If so, please add that to the comment.

> +
> +	ax45mp_priv = devm_kzalloc(&pdev->dev, sizeof(*ax45mp_priv), GFP_KERNEL);
> +	if (!ax45mp_priv)
> +		return -ENOMEM;
> +
> +	ax45mp_priv->l2c_base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(ax45mp_priv->l2c_base))
> +		return PTR_ERR(ax45mp_priv->l2c_base);
> +
> +	ax45mp_get_l2_line_size(pdev);
> +
> +	memset(&ax45mp_cmo_ops, 0x0, sizeof(ax45mp_cmo_ops));
> +	ax45mp_cmo_ops.riscv_dma_noncoherent_cmo_ops = &ax45mp_no_iocp_cmo;

Yah, drop this dance and use a static struct foo_ops construct please.

With those two, I'm happy with this I guess..
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

> +	riscv_noncoherent_register_cache_ops(&ax45mp_cmo_ops);
> +
> +	return 0;
> +}
> +
> +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)
> +{
> +	return platform_driver_register(&ax45mp_l2c_driver);
> +}
> +arch_initcall(ax45mp_cache_init);
> +
> +MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
> +MODULE_DESCRIPTION("Andes AX45MP L2 cache driver");
> +MODULE_LICENSE("GPL");

BTW, I think these are surplus-to-requirements since this is never going
to be built as a module.

If you resurrect the directory level maintainers entry from my v5.1, you
can also add:
Acked-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
Conor.
Lad, Prabhakar Jan. 7, 2023, 8:49 p.m. UTC | #2
Hi Conor,

Thank you for the review.

On Sat, Jan 7, 2023 at 12:09 AM Conor Dooley <conor@kernel.org> wrote:
>
> On Fri, Jan 06, 2023 at 06:55:25PM +0000, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >
> > 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: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
>
> > diff --git a/drivers/cache/ax45mp_cache.c b/drivers/cache/ax45mp_cache.c
> > new file mode 100644
> > index 000000000000..556e6875627c
> > --- /dev/null
> > +++ b/drivers/cache/ax45mp_cache.c
> > @@ -0,0 +1,279 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * non-coherent cache functions for Andes AX45MP
> > + *
> > + * Copyright (C) 2022 Renesas Electronics Corp.
> > + */
> > +
> > +#include <asm/dma-noncoherent.h>
> > +#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>
>
> You don't actually need this anymore, do you?
>
Agreed these can be dropped now.

> > +static int ax45mp_l2c_probe(struct platform_device *pdev)
> > +{
> > +     struct riscv_cache_ops ax45mp_cmo_ops;
> > +
> > +     /*
> > +      * riscv_cbom_block_size is set very much earlier so we can
> > +      * definitely rely on it and only if its being set we continue
> > +      * further in the probe path.
> > +      */
> > +     if (!riscv_cbom_block_size)
> > +             return 0;
>
> Return 0? That's because we may actually have the IOCP & do not want to
> install ops, right?
> If so, please add that to the comment.
>
OK, I will add that.

> > +
> > +     ax45mp_priv = devm_kzalloc(&pdev->dev, sizeof(*ax45mp_priv), GFP_KERNEL);
> > +     if (!ax45mp_priv)
> > +             return -ENOMEM;
> > +
> > +     ax45mp_priv->l2c_base = devm_platform_ioremap_resource(pdev, 0);
> > +     if (IS_ERR(ax45mp_priv->l2c_base))
> > +             return PTR_ERR(ax45mp_priv->l2c_base);
> > +
> > +     ax45mp_get_l2_line_size(pdev);
> > +
> > +     memset(&ax45mp_cmo_ops, 0x0, sizeof(ax45mp_cmo_ops));
> > +     ax45mp_cmo_ops.riscv_dma_noncoherent_cmo_ops = &ax45mp_no_iocp_cmo;
>
> Yah, drop this dance and use a static struct foo_ops construct please.
>
Will do.

> With those two, I'm happy with this I guess..
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
>
> > +     riscv_noncoherent_register_cache_ops(&ax45mp_cmo_ops);
> > +
> > +     return 0;
> > +}
> > +
> > +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)
> > +{
> > +     return platform_driver_register(&ax45mp_l2c_driver);
> > +}
> > +arch_initcall(ax45mp_cache_init);
> > +
> > +MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
> > +MODULE_DESCRIPTION("Andes AX45MP L2 cache driver");
> > +MODULE_LICENSE("GPL");
>
> BTW, I think these are surplus-to-requirements since this is never going
> to be built as a module.
>
Agreed, I will drop it.

> If you resurrect the directory level maintainers entry from my v5.1, you
> can also add:
Sure I'll add it in the next version..

> Acked-by: Conor Dooley <conor.dooley@microchip.com>
>
... and also include your ACK.

Cheers,
Prabhakar
diff mbox series

Patch

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 968bd0a6fd78..44abd2cba3a3 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -15,6 +15,8 @@  source "drivers/base/Kconfig"
 
 source "drivers/bus/Kconfig"
 
+source "drivers/cache/Kconfig"
+
 source "drivers/connector/Kconfig"
 
 source "drivers/firmware/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index bdf1c66141c9..9fc91d2bbe4c 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -6,6 +6,7 @@ 
 # Rewritten to use lists instead of if-statements.
 #
 
+obj-y				+= cache/
 obj-y				+= irqchip/
 obj-y				+= bus/
 
diff --git a/drivers/cache/Kconfig b/drivers/cache/Kconfig
new file mode 100644
index 000000000000..5478adff3d88
--- /dev/null
+++ b/drivers/cache/Kconfig
@@ -0,0 +1,10 @@ 
+# SPDX-License-Identifier: GPL-2.0
+menu "Cache Drivers"
+
+config AX45MP_L2_CACHE
+	bool "Andes Technology AX45MP L2 Cache controller"
+	depends on RISCV && RISCV_DMA_NONCOHERENT
+	help
+	  Support for the L2 cache controller on Andes Technology AX45MP platforms.
+
+endmenu
diff --git a/drivers/cache/Makefile b/drivers/cache/Makefile
new file mode 100644
index 000000000000..2012e7fb978d
--- /dev/null
+++ b/drivers/cache/Makefile
@@ -0,0 +1,3 @@ 
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_AX45MP_L2_CACHE) += ax45mp_cache.o
diff --git a/drivers/cache/ax45mp_cache.c b/drivers/cache/ax45mp_cache.c
new file mode 100644
index 000000000000..556e6875627c
--- /dev/null
+++ b/drivers/cache/ax45mp_cache.c
@@ -0,0 +1,279 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * non-coherent cache functions for Andes AX45MP
+ *
+ * Copyright (C) 2022 Renesas Electronics Corp.
+ */
+
+#include <asm/dma-noncoherent.h>
+#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>
+
+/* 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 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_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);
+}
+
+/*
+ * Software trigger CCTL operation (cache maintenance operations) by writing
+ * to ucctlcommand and ucctlbeginaddr registers and write-back an L2 cache
+ * entry.
+ */
+static void ax45mp_cpu_dcache_wb_range(void *start, void *end, int 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, AX45MP_CCTL_L1D_VA_WB);
+
+		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;
+	}
+}
+
+/*
+ * Software trigger CCTL operation by writing to ucctlcommand and ucctlbeginaddr
+ * registers and invalidate the L2 cache entry.
+ */
+static void ax45mp_cpu_dcache_inval_range(void *start, void *end, int 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, AX45MP_CCTL_L1D_VA_INVAL);
+
+		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_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 (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);
+
+	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)));
+
+	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;
+
+	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);
+}
+
+static void ax45mp_no_iocp_cmo(void *vaddr, size_t size,
+			       enum dma_data_direction dir,
+			       enum dma_noncoherent_ops ops)
+{
+	/* We have nothing to do in case of NON_COHERENT_DMA_PREP */
+	if (ops != NON_COHERENT_SYNC_DMA_FOR_DEVICE &&
+	    ops != NON_COHERENT_SYNC_DMA_FOR_CPU)
+		return;
+
+	/*
+	 * In case of DMA_FROM_DEVICE invalidate the L2 cache entries and
+	 * in case of DMA_TO_DEVICE and DMA_BIDIRECTIONAL write-back an L2
+	 * cache entries.
+	 */
+	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;
+	}
+
+	/*
+	 * ops == NON_COHERENT_SYNC_DMA_FOR_CPU
+	 *
+	 * in case of DMA_BIDIRECTIONAL and DMA_FROM_DEVICE invalidate the L2
+	 * cache entries.
+	 */
+	if (dir == DMA_BIDIRECTIONAL || dir == DMA_FROM_DEVICE)
+		ax45mp_cpu_dma_inval_range(vaddr, size);
+}
+
+static void ax45mp_get_l2_line_size(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = of_property_read_u32(np, "cache-line-size", &ax45mp_priv->ax45mp_cache_line_size);
+	if (ret) {
+		dev_err(dev, "Failed to get cache-line-size, defaulting to 64 bytes\n");
+		ax45mp_priv->ax45mp_cache_line_size = AX45MP_CACHE_LINE_SIZE;
+	}
+
+	if (ax45mp_priv->ax45mp_cache_line_size != AX45MP_CACHE_LINE_SIZE) {
+		dev_err(dev, "Expected cache-line-size to be 64 bytes (found:%u). Defaulting to 64 bytes\n",
+			ax45mp_priv->ax45mp_cache_line_size);
+		ax45mp_priv->ax45mp_cache_line_size = AX45MP_CACHE_LINE_SIZE;
+	}
+}
+
+static int ax45mp_l2c_probe(struct platform_device *pdev)
+{
+	struct riscv_cache_ops ax45mp_cmo_ops;
+
+	/*
+	 * riscv_cbom_block_size is set very much earlier so we can
+	 * definitely rely on it and only if its being set we continue
+	 * further in the probe path.
+	 */
+	if (!riscv_cbom_block_size)
+		return 0;
+
+	ax45mp_priv = devm_kzalloc(&pdev->dev, sizeof(*ax45mp_priv), GFP_KERNEL);
+	if (!ax45mp_priv)
+		return -ENOMEM;
+
+	ax45mp_priv->l2c_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(ax45mp_priv->l2c_base))
+		return PTR_ERR(ax45mp_priv->l2c_base);
+
+	ax45mp_get_l2_line_size(pdev);
+
+	memset(&ax45mp_cmo_ops, 0x0, sizeof(ax45mp_cmo_ops));
+	ax45mp_cmo_ops.riscv_dma_noncoherent_cmo_ops = &ax45mp_no_iocp_cmo;
+	riscv_noncoherent_register_cache_ops(&ax45mp_cmo_ops);
+
+	return 0;
+}
+
+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)
+{
+	return platform_driver_register(&ax45mp_l2c_driver);
+}
+arch_initcall(ax45mp_cache_init);
+
+MODULE_AUTHOR("Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>");
+MODULE_DESCRIPTION("Andes AX45MP L2 cache driver");
+MODULE_LICENSE("GPL");