4 files changed, 147 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
new file mode 100644
index 000000000000..4d0a00e453a8
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/sram.txt
@@ -0,0 +1,16 @@
+Generic on-chip SRAM
+
+Simple IO memory regions to be managed by the genalloc API.
+
+Required properties:
+
+- compatible : mmio-sram
+
+- reg : SRAM iomem address range
+
+Example:
+
+sram: sram@5c000000 {
+        compatible = "mmio-sram";
+        reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
+};
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index e29e7980a359..3659d00efdc5 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -518,6 +518,15 @@ config LATTICE_ECP3_CONFIG
 
           If unsure, say N.
 
+config SRAM
+        bool "Generic on-chip SRAM driver"
+        depends on HAS_IOMEM
+        select GENERIC_ALLOCATOR
+        help
+          This driver allows you 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 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 865cbc6a7ae1..c235d5b68311 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -52,3 +52,4 @@ obj-$(CONFIG_ALTERA_STAPL)	+=altera-stapl/
 obj-$(CONFIG_INTEL_MEI)         += mei/
 obj-$(CONFIG_VMWARE_VMCI)       += vmw_vmci/
 obj-$(CONFIG_LATTICE_ECP3_CONFIG)       += lattice-ecp3-config.o
+obj-$(CONFIG_SRAM)              += sram.o
diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
new file mode 100644
index 000000000000..437192e43006
--- /dev/null
+++ b/drivers/misc/sram.c
@@ -0,0 +1,121 @@
+/*
+ * 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/init.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/genalloc.h>
+
+#define SRAM_GRANULARITY        32
+
+struct sram_dev {
+        struct gen_pool *pool;
+        struct clk *clk;
+};
+
+static int 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->clk = devm_clk_get(&pdev->dev, NULL);
+        if (IS_ERR(sram->clk))
+                sram->clk = NULL;
+        else
+                clk_prepare_enable(sram->clk);
+
+        sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -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 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);
+
+        if (sram->clk)
+                clk_disable_unprepare(sram->clk);
+
+        return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id sram_dt_ids[] = {
+        { .compatible = "mmio-sram" },
+        {}
+};
+#endif
+
+static struct platform_driver sram_driver = {
+        .driver = {
+                .name = "sram",
+                .of_match_table = of_match_ptr(sram_dt_ids),
+        },
+        .probe = sram_probe,
+        .remove = sram_remove,
+};
+
+static int __init sram_init(void)
+{
+        return platform_driver_register(&sram_driver);
+}
+
+postcore_initcall(sram_init);