diff mbox series

[04/12] soc: sifive: ccache: Add non-coherent DMA handling

Message ID 20230211031821.976408-5-cristian.ciocaltea@collabora.com
State New
Headers show
Series Enable networking support for StarFive JH7100 SoC | expand

Commit Message

Cristian Ciocaltea Feb. 11, 2023, 3:18 a.m. UTC 
From: Emil Renner Berthing <kernel@esmil.dk>

Add functions to flush the caches and handle non-coherent DMA.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
[replace <asm/cacheflush.h> with <linux/cacheflush.h>]
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/soc/sifive/sifive_ccache.c | 60 +++++++++++++++++++++++++++++-
 include/soc/sifive/sifive_ccache.h | 21 +++++++++++
 2 files changed, 80 insertions(+), 1 deletion(-)

Comments

Conor Dooley Feb. 16, 2023, 6:50 p.m. UTC | #1 
Emil,

+CC Daire

On Sat, Feb 11, 2023 at 05:18:13AM +0200, Cristian Ciocaltea wrote:
> From: Emil Renner Berthing <kernel@esmil.dk>
> 
> Add functions to flush the caches and handle non-coherent DMA.
> 
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> [replace <asm/cacheflush.h> with <linux/cacheflush.h>]
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---

> +void *sifive_ccache_set_uncached(void *addr, size_t size)
> +{
> +	phys_addr_t phys_addr = __pa(addr) + uncached_offset;
> +	void *mem_base;
> +
> +	mem_base = memremap(phys_addr, size, MEMREMAP_WT);
> +	if (!mem_base) {
> +		pr_err("%s memremap failed for addr %p\n", __func__, addr);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	return mem_base;
> +}

The rest of this I either get b/c we did it, or will become moot so I
amn't worried about it, but can you please explain this, in particular
the memremap that you're doing here?

Cheers,
Conor.
Emil Renner Berthing Feb. 19, 2023, 9:32 p.m. UTC | #2 
On Thu, 16 Feb 2023 at 19:51, Conor Dooley <conor@kernel.org> wrote:
>
> Emil,
>
> +CC Daire
>
> On Sat, Feb 11, 2023 at 05:18:13AM +0200, Cristian Ciocaltea wrote:
> > From: Emil Renner Berthing <kernel@esmil.dk>
> >
> > Add functions to flush the caches and handle non-coherent DMA.
> >
> > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > [replace <asm/cacheflush.h> with <linux/cacheflush.h>]
> > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> > ---
>
> > +void *sifive_ccache_set_uncached(void *addr, size_t size)
> > +{
> > +     phys_addr_t phys_addr = __pa(addr) + uncached_offset;
> > +     void *mem_base;
> > +
> > +     mem_base = memremap(phys_addr, size, MEMREMAP_WT);
> > +     if (!mem_base) {
> > +             pr_err("%s memremap failed for addr %p\n", __func__, addr);
> > +             return ERR_PTR(-EINVAL);
> > +     }
> > +
> > +     return mem_base;
> > +}
>
> The rest of this I either get b/c we did it, or will become moot so I
> amn't worried about it, but can you please explain this, in particular
> the memremap that you're doing here?

No, I can't really. As we talked about it's also based on a prototype
by Atish. I'm sure you know that the general idea is that we want to
return a pointer that accesses the same physical memory, but through
the uncached alias. I can't tell you exactly why it's done this way
though, sorry.

/Emil

> Cheers,
> Conor.
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
Conor Dooley Feb. 20, 2023, 11:43 a.m. UTC | #3 
On Sun, Feb 19, 2023 at 10:32:52PM +0100, Emil Renner Berthing wrote:
> On Thu, 16 Feb 2023 at 19:51, Conor Dooley <conor@kernel.org> wrote:
> >
> > Emil,
> >
> > +CC Daire
> >
> > On Sat, Feb 11, 2023 at 05:18:13AM +0200, Cristian Ciocaltea wrote:
> > > From: Emil Renner Berthing <kernel@esmil.dk>
> > >
> > > Add functions to flush the caches and handle non-coherent DMA.
> > >
> > > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > > [replace <asm/cacheflush.h> with <linux/cacheflush.h>]
> > > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> > > ---
> >
> > > +void *sifive_ccache_set_uncached(void *addr, size_t size)
> > > +{
> > > +     phys_addr_t phys_addr = __pa(addr) + uncached_offset;
> > > +     void *mem_base;
> > > +
> > > +     mem_base = memremap(phys_addr, size, MEMREMAP_WT);
> > > +     if (!mem_base) {
> > > +             pr_err("%s memremap failed for addr %p\n", __func__, addr);
> > > +             return ERR_PTR(-EINVAL);
> > > +     }
> > > +
> > > +     return mem_base;
> > > +}
> >
> > The rest of this I either get b/c we did it, or will become moot so I
> > amn't worried about it, but can you please explain this, in particular
> > the memremap that you're doing here?
> 
> No, I can't really. As we talked about it's also based on a prototype
> by Atish. I'm sure you know that the general idea is that we want to
> return a pointer that accesses the same physical memory, but through
> the uncached alias.

Yah, I follow all the rest of what's going on - it's just this bit of it
that I don't.

> I can't tell you exactly why it's done this way
> though, sorry.

I had a bit of a look on lore, but don't really see anything there that
contained any discussion of what was going on here.

Adding Atish in the off-chance that he remembers!
diff mbox series

Patch

diff --git a/drivers/soc/sifive/sifive_ccache.c b/drivers/soc/sifive/sifive_ccache.c
index 676468c35859..0062635d845f 100644
--- a/drivers/soc/sifive/sifive_ccache.c
+++ b/drivers/soc/sifive/sifive_ccache.c
@@ -8,13 +8,16 @@ 
 
 #define pr_fmt(fmt) "CCACHE: " fmt
 
+#include <linux/align.h>
 #include <linux/debugfs.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
 #include <linux/of_address.h>
 #include <linux/device.h>
 #include <linux/bitfield.h>
+#include <linux/cacheflush.h>
 #include <asm/cacheinfo.h>
+#include <asm/page.h>
 #include <soc/sifive/sifive_ccache.h>
 
 #define SIFIVE_CCACHE_DIRECCFIX_LOW 0x100
@@ -39,10 +42,14 @@ 
 #define SIFIVE_CCACHE_CONFIG_SETS_MASK GENMASK_ULL(23, 16)
 #define SIFIVE_CCACHE_CONFIG_BLKS_MASK GENMASK_ULL(31, 24)
 
+#define SIFIVE_CCACHE_FLUSH64 0x200
+#define SIFIVE_CCACHE_FLUSH32 0x240
+
 #define SIFIVE_CCACHE_WAYENABLE 0x08
 #define SIFIVE_CCACHE_ECCINJECTERR 0x40
 
 #define SIFIVE_CCACHE_MAX_ECCINTR 4
+#define SIFIVE_CCACHE_LINE_SIZE 64
 
 static void __iomem *ccache_base;
 static int g_irq[SIFIVE_CCACHE_MAX_ECCINTR];
@@ -125,6 +132,47 @@  int unregister_sifive_ccache_error_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL_GPL(unregister_sifive_ccache_error_notifier);
 
+#ifdef CONFIG_RISCV_DMA_NONCOHERENT
+static phys_addr_t uncached_offset;
+DEFINE_STATIC_KEY_FALSE(sifive_ccache_handle_noncoherent_key);
+
+void sifive_ccache_flush_range(phys_addr_t start, size_t len)
+{
+	phys_addr_t end = start + len;
+	phys_addr_t line;
+
+	if (!len)
+		return;
+
+	mb();
+	for (line = ALIGN_DOWN(start, SIFIVE_CCACHE_LINE_SIZE); line < end;
+			line += SIFIVE_CCACHE_LINE_SIZE) {
+#ifdef CONFIG_32BIT
+		writel(line >> 4, ccache_base + SIFIVE_CCACHE_FLUSH32);
+#else
+		writeq(line, ccache_base + SIFIVE_CCACHE_FLUSH64);
+#endif
+		mb();
+	}
+}
+EXPORT_SYMBOL_GPL(sifive_ccache_flush_range);
+
+void *sifive_ccache_set_uncached(void *addr, size_t size)
+{
+	phys_addr_t phys_addr = __pa(addr) + uncached_offset;
+	void *mem_base;
+
+	mem_base = memremap(phys_addr, size, MEMREMAP_WT);
+	if (!mem_base) {
+		pr_err("%s memremap failed for addr %p\n", __func__, addr);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return mem_base;
+}
+EXPORT_SYMBOL_GPL(sifive_ccache_set_uncached);
+#endif /* CONFIG_RISCV_DMA_NONCOHERENT */
+
 static int ccache_largest_wayenabled(void)
 {
 	return readl(ccache_base + SIFIVE_CCACHE_WAYENABLE) & 0xFF;
@@ -213,6 +261,7 @@  static int __init sifive_ccache_init(void)
 	int i, rc, intr_num;
 	const struct of_device_id *match;
 	unsigned long broken_irqs;
+	u64 __maybe_unused offset;
 
 	np = of_find_matching_node_and_match(NULL, sifive_ccache_ids, &match);
 	if (!np)
@@ -258,6 +307,15 @@  static int __init sifive_ccache_init(void)
 	}
 	of_node_put(np);
 
+#ifdef CONFIG_RISCV_DMA_NONCOHERENT
+	if (!of_property_read_u64(np, "uncached-offset", &offset)) {
+		uncached_offset = offset;
+		static_branch_enable(&sifive_ccache_handle_noncoherent_key);
+		riscv_cbom_block_size = SIFIVE_CCACHE_LINE_SIZE;
+		riscv_noncoherent_supported();
+	}
+#endif
+
 	ccache_config_read();
 
 	ccache_cache_ops.get_priv_group = ccache_get_priv_group;
@@ -278,4 +336,4 @@  static int __init sifive_ccache_init(void)
 	return rc;
 }
 
-device_initcall(sifive_ccache_init);
+arch_initcall(sifive_ccache_init);
diff --git a/include/soc/sifive/sifive_ccache.h b/include/soc/sifive/sifive_ccache.h
index 4d4ed49388a0..d349ccb3969b 100644
--- a/include/soc/sifive/sifive_ccache.h
+++ b/include/soc/sifive/sifive_ccache.h
@@ -7,10 +7,31 @@ 
 #ifndef __SOC_SIFIVE_CCACHE_H
 #define __SOC_SIFIVE_CCACHE_H
 
+#include <linux/io.h>
+#include <linux/jump_label.h>
+
 extern int register_sifive_ccache_error_notifier(struct notifier_block *nb);
 extern int unregister_sifive_ccache_error_notifier(struct notifier_block *nb);
 
 #define SIFIVE_CCACHE_ERR_TYPE_CE 0
 #define SIFIVE_CCACHE_ERR_TYPE_UE 1
 
+DECLARE_STATIC_KEY_FALSE(sifive_ccache_handle_noncoherent_key);
+
+static inline bool sifive_ccache_handle_noncoherent(void)
+{
+#ifdef CONFIG_SIFIVE_CCACHE
+	return static_branch_unlikely(&sifive_ccache_handle_noncoherent_key);
+#else
+	return false;
+#endif
+}
+
+void sifive_ccache_flush_range(phys_addr_t start, size_t len);
+void *sifive_ccache_set_uncached(void *addr, size_t size);
+static inline void sifive_ccache_clear_uncached(void *addr, size_t size)
+{
+	memunmap(addr);
+}
+
 #endif /* __SOC_SIFIVE_CCACHE_H */