[PATCH v3 0/4] Add device tree support for on-chip SRAM

[PATCH v3 0/4] Add device tree support for on-chip SRAM

[Philipp Zabel]

These patches add support to configure on-chip SRAM via device-tree
node and to obtain the resulting genalloc pool from a phandle pointing
at the node.
This allows drivers to allocate SRAM with the genalloc API without
hard-coding the genalloc pool address.

The on-chip SRAM on i.MX53 and i.MX6q is registered via device tree and
changed to use the simple generic SRAM driver:

		ocram: ocram@00900000 {
			compatible = "fsl,imx-ocram", "sram";
			reg = <0x00900000 0x3f000>;
 		};

A driver that needs to allocate SRAM buffers, like the video processing
unit on i.MX53, can retrieve the genalloc pool from a phandle in the
device tree using of_get_named_gen_pool(node, "iram", 0) from patch 5:

		vpu@63ff4000 {
			/* ... */
			iram = <&ocram>;
 		};

Changes since v2, as per Shawn's suggestions:
 - Moved struct device_node declaration out of #ifdef CONFIG_OF.
 - Simplified of_get_named_gen_pool using of_parse_phandle and
   of_address_to_resource.
 - Return -EADDRNOTAVAIL if devm_request_and_ioremap fails.
 - Squashed i.MX changes together.

regards
Philipp

---
 arch/arm/boot/dts/imx53.dtsi          |    5 ++
 arch/arm/boot/dts/imx6q.dtsi          |    5 ++
 arch/arm/plat-mxc/Kconfig             |    4 --
 arch/arm/plat-mxc/Makefile            |    1 -
 arch/arm/plat-mxc/include/mach/iram.h |   41 -------------
 arch/arm/plat-mxc/iram_alloc.c        |   73 -----------------------
 drivers/misc/Kconfig                  |    9 +++
 drivers/misc/Makefile                 |    1 +
 drivers/misc/sram.c                   |  105 +++++++++++++++++++++++++++++++++
 include/linux/genalloc.h              |   14 +++++
 lib/genalloc.c                        |   67 +++++++++++++++++++++
 11 files changed, 206 insertions(+), 119 deletions(-)

[PATCH v3 1/4] genalloc: add a global pool list, allow to find pools by phys address

[Philipp Zabel]

This patch keeps all created pools in a global list and adds two
functions that allow to retrieve the gen_pool pointer from a known
physical address and from a device tree node.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Changes since v2:
 - Moved struct device_node declaration out of #ifdef CONFIG_OF.
 - Simplified of_get_named_gen_pool using of_parse_phandle and
   of_address_to_resource.
---
 include/linux/genalloc.h |   14 ++++++++++
 lib/genalloc.c           |   67 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 81 insertions(+)

diff --git a/include/linux/genalloc.h b/include/linux/genalloc.h
index 5e98eeb..d498c43 100644
--- a/include/linux/genalloc.h
+++ b/include/linux/genalloc.h
@@ -33,6 +33,7 @@
  *  General purpose special memory pool descriptor.
  */
 struct gen_pool {
+	struct list_head next_pool;	/* pool in global list */
 	spinlock_t lock;
 	struct list_head chunks;	/* list of chunks in this pool */
 	int min_alloc_order;		/* minimum allocation order */
@@ -78,4 +79,17 @@ extern void gen_pool_for_each_chunk(struct gen_pool *,
 	void (*)(struct gen_pool *, struct gen_pool_chunk *, void *), void *);
 extern size_t gen_pool_avail(struct gen_pool *);
 extern size_t gen_pool_size(struct gen_pool *);
+extern struct gen_pool *gen_pool_find_by_phys(phys_addr_t phys);
+
+struct device_node;
+#ifdef CONFIG_OF
+extern struct gen_pool *of_get_named_gen_pool(struct device_node *np,
+	const char *propname, int index);
+#else
+inline struct gen_pool *of_get_named_gen_pool(struct device_node *np,
+	const char *propname, int index)
+{
+	return NULL;
+}
+#endif
 #endif /* __GENALLOC_H__ */
diff --git a/lib/genalloc.c b/lib/genalloc.c
index 6bc04aa..90699ac 100644
--- a/lib/genalloc.c
+++ b/lib/genalloc.c
@@ -34,6 +34,11 @@
 #include <linux/rculist.h>
 #include <linux/interrupt.h>
 #include <linux/genalloc.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+
+static LIST_HEAD(pools);
+static DEFINE_SPINLOCK(list_lock);
 
 static int set_bits_ll(unsigned long *addr, unsigned long mask_to_set)
 {
@@ -152,6 +157,9 @@ struct gen_pool *gen_pool_create(int min_alloc_order, int nid)
 		spin_lock_init(&pool->lock);
 		INIT_LIST_HEAD(&pool->chunks);
 		pool->min_alloc_order = min_alloc_order;
+		spin_lock(&list_lock);
+		list_add_rcu(&pool->next_pool, &pools);
+		spin_unlock(&list_lock);
 	}
 	return pool;
 }
@@ -234,6 +242,9 @@ void gen_pool_destroy(struct gen_pool *pool)
 	int order = pool->min_alloc_order;
 	int bit, end_bit;
 
+	spin_lock(&list_lock);
+	list_del_rcu(&pool->next_pool);
+	spin_unlock(&list_lock);
 	list_for_each_safe(_chunk, _next_chunk, &pool->chunks) {
 		chunk = list_entry(_chunk, struct gen_pool_chunk, next_chunk);
 		list_del(&chunk->next_chunk);
@@ -400,3 +411,59 @@ size_t gen_pool_size(struct gen_pool *pool)
 	return size;
 }
 EXPORT_SYMBOL_GPL(gen_pool_size);
+
+/**
+ * gen_pool_find_by_phys - find a pool by physical start address
+ * @phys: physical address as added with gen_pool_add_virt
+ *
+ * Returns the pool that contains the chunk starting at phys,
+ * or NULL if not found.
+ */
+struct gen_pool *gen_pool_find_by_phys(phys_addr_t phys)
+{
+	struct gen_pool *pool, *found = NULL;
+	struct gen_pool_chunk *chunk;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pool, &pools, next_pool) {
+		list_for_each_entry_rcu(chunk, &pool->chunks, next_chunk) {
+			if (phys == chunk->phys_addr) {
+				found = pool;
+				break;
+			}
+		}
+	}
+	rcu_read_unlock();
+
+	return found;
+}
+EXPORT_SYMBOL_GPL(gen_pool_find_by_phys);
+
+#ifdef CONFIG_OF
+/**
+ * of_get_named_gen_pool - find a pool by phandle property
+ * @np: device node
+ * @propname: property name containing phandle(s)
+ * @index: index into the phandle array
+ *
+ * Returns the pool that contains the chunk starting at the physical
+ * address of the device tree node pointed at by the phandle property,
+ * or NULL if not found.
+ */
+struct gen_pool *of_get_named_gen_pool(struct device_node *np,
+	const char *propname, int index)
+{
+	struct device_node *np_pool;
+	struct resource res;
+	int ret;
+
+	np_pool = of_parse_phandle(np, propname, index);
+	if (!np_pool)
+		return NULL;
+	ret = of_address_to_resource(np_pool, 0, &res);
+	if (ret < 0)
+		return NULL;
+	return gen_pool_find_by_phys((phys_addr_t) res.start);
+}
+EXPORT_SYMBOL_GPL(of_get_named_gen_pool);
+#endif /* CONFIG_OF */
-- 
1.7.10.4

[PATCH v3 2/4] misc: Generic on-chip SRAM allocation driver

[Philipp Zabel]

This driver requests and remaps a memory region as configured in the
device tree. It serves memory from this region via the genalloc API.

Other drivers can retrieve the genalloc pool from a phandle pointing
to this drivers' device node in the device tree.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Changes since v2:
 - Return -EADDRNOTAVAIL if devm_request_and_ioremap fails.
---
 drivers/misc/Kconfig  |    9 +++++
 drivers/misc/Makefile |    1 +
 drivers/misc/sram.c   |  105 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 drivers/misc/sram.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 98a442d..9a3395f 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -509,6 +509,15 @@ config USB_SWITCH_FSA9480
 	  stereo and mono audio, video, microphone and UART data to use
 	  a common connector port.
 
+config SRAM
+	bool "Generic on-chip SRAM driver"
+	depends on HAS_IOMEM
+	select GENERIC_ALLOCATOR
+	help
+	  This driver allows to declare a memory region to be managed
+	  by the genalloc API. It is supposed to be used for small
+	  on-chip SRAM areas found on many ARM SoCs.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index b88df7a..ccc759a 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -50,3 +50,4 @@ obj-y				+= carma/
 obj-$(CONFIG_USB_SWITCH_FSA9480) += fsa9480.o
 obj-$(CONFIG_ALTERA_STAPL)	+=altera-stapl/
 obj-$(CONFIG_INTEL_MEI)		+= mei/
+obj-$(CONFIG_SRAM)		+= sram.o
diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
new file mode 100644
index 0000000..d6e1230
--- /dev/null
+++ b/drivers/misc/sram.c
@@ -0,0 +1,105 @@
+/*
+ * Generic on-chip SRAM allocation driver
+ *
+ * Copyright (C) 2012 Philipp Zabel, Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/genalloc.h>
+
+struct sram_dev {
+	struct gen_pool *pool;
+};
+
+static int __devinit sram_probe(struct platform_device *pdev)
+{
+	void __iomem *virt_base;
+	struct sram_dev *sram;
+	struct resource *res;
+	unsigned long size;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	size = resource_size(res);
+
+	virt_base = devm_request_and_ioremap(&pdev->dev, res);
+	if (!virt_base)
+		return -EADDRNOTAVAIL;
+
+	sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
+	if (!sram)
+		return -ENOMEM;
+
+	sram->pool = gen_pool_create(PAGE_SHIFT, -1);
+	if (!sram->pool)
+		return -ENOMEM;
+
+	ret = gen_pool_add_virt(sram->pool, (unsigned long)virt_base,
+				res->start, size, -1);
+	if (ret < 0) {
+		gen_pool_destroy(sram->pool);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, sram);
+
+	dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
+
+	return 0;
+}
+
+static int __devexit sram_remove(struct platform_device *pdev)
+{
+	struct sram_dev *sram = platform_get_drvdata(pdev);
+
+	if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
+		dev_dbg(&pdev->dev, "removed while SRAM allocated\n");
+
+	gen_pool_destroy(sram->pool);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id sram_dt_ids[] = {
+	{ .compatible = "sram" },
+	{ /* sentinel */ }
+};
+#endif
+
+static struct platform_driver sram_driver = {
+	.driver = {
+		.name = "sram",
+		.of_match_table = of_match_ptr(sram_dt_ids),
+	},
+	.probe = sram_probe,
+	.remove = __devexit_p(sram_remove),
+};
+
+module_platform_driver(sram_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Philipp Zabel, Pengutronix");
+MODULE_DESCRIPTION("Generic SRAM allocator driver");
-- 
1.7.10.4

[PATCH v3 3/4] ARM: dts: add sram for imx53 and imx6q

[Philipp Zabel]

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 arch/arm/boot/dts/imx53.dtsi |    5 +++++
 arch/arm/boot/dts/imx6q.dtsi |    5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/arm/boot/dts/imx53.dtsi b/arch/arm/boot/dts/imx53.dtsi
index cd37165..2767a92 100644
--- a/arch/arm/boot/dts/imx53.dtsi
+++ b/arch/arm/boot/dts/imx53.dtsi
@@ -337,5 +337,10 @@
 				status = "disabled";
 			};
 		};
+
+		ocram: ocram@f8000000 {
+			compatible = "fsl,imx-ocram", "sram";
+			reg = <0xf8000000 0x20000>;
+		};
 	};
 };
diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi
index fd57079..1e463c4 100644
--- a/arch/arm/boot/dts/imx6q.dtsi
+++ b/arch/arm/boot/dts/imx6q.dtsi
@@ -111,6 +111,11 @@
 		       status = "disabled";
 		};
 
+		ocram: ocram@00900000 {
+			compatible = "fsl,imx-ocram", "sram";
+			reg = <0x00900000 0x3f000>;
+		};
+
 		timer@00a00600 {
 			compatible = "arm,cortex-a9-twd-timer";
 			reg = <0x00a00600 0x20>;
-- 
1.7.10.4

[PATCH v3 4/4] ARM i.MX: remove IRAM_ALLOC facility

[Philipp Zabel]

A generic on-chip SRAM allocator driver can be used instead.
Users of the iram_alloc/free API should convert to the genalloc API:

-	virt = iram_alloc(SIZE, &phys);
+	gen_pool_alloc(iram_pool, SIZE);
+	phys = gen_pool_virt_to_phys(iram_pool, virt);
 	/* ... */
-	iram_free(virt, SIZE);
+	gen_pool_free(iram_pool, virt, SIZE);

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 arch/arm/plat-mxc/Kconfig             |    4 --
 arch/arm/plat-mxc/Makefile            |    1 -
 arch/arm/plat-mxc/include/mach/iram.h |   41 ------------------
 arch/arm/plat-mxc/iram_alloc.c        |   73 ---------------------------------
 4 files changed, 119 deletions(-)
 delete mode 100644 arch/arm/plat-mxc/include/mach/iram.h
 delete mode 100644 arch/arm/plat-mxc/iram_alloc.c

diff --git a/arch/arm/plat-mxc/Kconfig b/arch/arm/plat-mxc/Kconfig
index baf9064..8e63f10 100644
--- a/arch/arm/plat-mxc/Kconfig
+++ b/arch/arm/plat-mxc/Kconfig
@@ -82,8 +82,4 @@ config IMX_HAVE_IOMUX_V1
 config ARCH_MXC_IOMUX_V3
 	bool
 
-config IRAM_ALLOC
-	bool
-	select GENERIC_ALLOCATOR
-
 endif
diff --git a/arch/arm/plat-mxc/Makefile b/arch/arm/plat-mxc/Makefile
index 6ac7200..bdf370f 100644
--- a/arch/arm/plat-mxc/Makefile
+++ b/arch/arm/plat-mxc/Makefile
@@ -10,7 +10,6 @@ obj-$(CONFIG_MXC_AVIC) += avic.o
 
 obj-$(CONFIG_IMX_HAVE_IOMUX_V1) += iomux-v1.o
 obj-$(CONFIG_ARCH_MXC_IOMUX_V3) += iomux-v3.o
-obj-$(CONFIG_IRAM_ALLOC) += iram_alloc.o
 obj-$(CONFIG_MXC_ULPI) += ulpi.o
 obj-$(CONFIG_MXC_USE_EPIT) += epit.o
 obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o
diff --git a/arch/arm/plat-mxc/include/mach/iram.h b/arch/arm/plat-mxc/include/mach/iram.h
deleted file mode 100644
index 022690c..0000000
--- a/arch/arm/plat-mxc/include/mach/iram.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
- * MA 02110-1301, USA.
- */
-#include <linux/errno.h>
-
-#ifdef CONFIG_IRAM_ALLOC
-
-int __init iram_init(unsigned long base, unsigned long size);
-void __iomem *iram_alloc(unsigned int size, unsigned long *dma_addr);
-void iram_free(unsigned long dma_addr, unsigned int size);
-
-#else
-
-static inline int __init iram_init(unsigned long base, unsigned long size)
-{
-	return -ENOMEM;
-}
-
-static inline void __iomem *iram_alloc(unsigned int size, unsigned long *dma_addr)
-{
-	return NULL;
-}
-
-static inline void iram_free(unsigned long base, unsigned long size) {}
-
-#endif
diff --git a/arch/arm/plat-mxc/iram_alloc.c b/arch/arm/plat-mxc/iram_alloc.c
deleted file mode 100644
index 074c386..0000000
--- a/arch/arm/plat-mxc/iram_alloc.c
+++ /dev/null
@@ -1,73 +0,0 @@
-/*
- * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
- * MA 02110-1301, USA.
- */
-
-#include <linux/kernel.h>
-#include <linux/io.h>
-#include <linux/module.h>
-#include <linux/spinlock.h>
-#include <linux/genalloc.h>
-#include <mach/iram.h>
-
-static unsigned long iram_phys_base;
-static void __iomem *iram_virt_base;
-static struct gen_pool *iram_pool;
-
-static inline void __iomem *iram_phys_to_virt(unsigned long p)
-{
-	return iram_virt_base + (p - iram_phys_base);
-}
-
-void __iomem *iram_alloc(unsigned int size, unsigned long *dma_addr)
-{
-	if (!iram_pool)
-		return NULL;
-
-	*dma_addr = gen_pool_alloc(iram_pool, size);
-	pr_debug("iram alloc - %dB@0x%lX\n", size, *dma_addr);
-	if (!*dma_addr)
-		return NULL;
-	return iram_phys_to_virt(*dma_addr);
-}
-EXPORT_SYMBOL(iram_alloc);
-
-void iram_free(unsigned long addr, unsigned int size)
-{
-	if (!iram_pool)
-		return;
-
-	gen_pool_free(iram_pool, addr, size);
-}
-EXPORT_SYMBOL(iram_free);
-
-int __init iram_init(unsigned long base, unsigned long size)
-{
-	iram_phys_base = base;
-
-	iram_pool = gen_pool_create(PAGE_SHIFT, -1);
-	if (!iram_pool)
-		return -ENOMEM;
-
-	gen_pool_add(iram_pool, base, size, -1);
-	iram_virt_base = ioremap(iram_phys_base, size);
-	if (!iram_virt_base)
-		return -EIO;
-
-	pr_debug("i.MX IRAM pool: %ld KB@0x%p\n", size / 1024, iram_virt_base);
-	return 0;
-}
-- 
1.7.10.4

Re: [PATCH v3 0/4] Add device tree support for on-chip SRAM

[Shawn Guo]

On Mon, Sep 03, 2012 at 06:02:04PM +0200, Philipp Zabel wrote:
> Changes since v2, as per Shawn's suggestions:
>  - Moved struct device_node declaration out of #ifdef CONFIG_OF.
>  - Simplified of_get_named_gen_pool using of_parse_phandle and
>    of_address_to_resource.
>  - Return -EADDRNOTAVAIL if devm_request_and_ioremap fails.
>  - Squashed i.MX changes together.
> 
For the series:

Reviewed-by: Shawn Guo <shawn.guo@linaro.org>

Though it will be very simple one, we may still need a binding doc for
that "sram" driver.

Regards,
Shawn

Re: [PATCH v3 2/4] misc: Generic on-chip SRAM allocation driver

[Shawn Guo]

On Mon, Sep 03, 2012 at 06:02:06PM +0200, Philipp Zabel wrote:
> +static struct platform_driver sram_driver = {
> +	.driver = {
> +		.name = "sram",
> +		.of_match_table = of_match_ptr(sram_dt_ids),
> +	},
> +	.probe = sram_probe,
> +	.remove = __devexit_p(sram_remove),
> +};
> +
> +module_platform_driver(sram_driver);

I think we'd better make it a postcore_initcall time driver, so that
it can be ensured that when the client drivers call gen_pool_* API
the pool has been created by sram_driver. 

-- 
Regards,
Shawn