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Date: Fri, 22 Mar 2013 13:47:44 +0100
From: Michal Simek <monstr@...str.eu>
To: Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-kernel@...r.kernel.org,
Fabio Estevam <fabio.estevam@...escale.com>,
Matt Porter <mporter@...com>,
Dong Aisheng <dong.aisheng@...aro.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
devicetree-discuss@...ts.ozlabs.org,
Rob Herring <rob.herring@...xeda.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Javier Martin <javier.martin@...ta-silicon.com>,
kernel@...gutronix.de, Huang Shijie <shijie8@...il.com>
Subject: Re: [PATCH v9 RESEND 2/4] misc: Generic on-chip SRAM allocation driver
2013/3/20 Philipp Zabel <p.zabel@...gutronix.de>:
> This driver requests and remaps a memory region as configured in the
> device tree. It serves memory from this region via the genalloc API.
> It optionally enables the SRAM clock.
>
> Other drivers can retrieve the genalloc pool from a phandle pointing
> to this drivers' device node in the device tree.
>
> The allocation granularity is hard-coded to 32 bytes for now,
> to make the SRAM driver useful for the 6502 remoteproc driver.
> There is overhead for bigger SRAMs, where only a much coarser
> allocation granularity is needed: At 32 bytes minimum allocation
> size, a 256 KiB SRAM needs a 1 KiB bitmap to track allocations.
>
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> Reviewed-by: Shawn Guo <shawn.guo@...aro.org>
> Acked-by: Grant Likely <grant.likely@...retlab.ca>
> ---
> Changes since v8:
> - Changed device tree compatible string to "mmio-sram"
> ---
> Documentation/devicetree/bindings/misc/sram.txt | 16 +++
> drivers/misc/Kconfig | 9 ++
> drivers/misc/Makefile | 1 +
> drivers/misc/sram.c | 121 +++++++++++++++++++++++
> 4 files changed, 147 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/sram.txt
> create mode 100644 drivers/misc/sram.c
>
> diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
> new file mode 100644
> index 0000000..4d0a00e
> --- /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@...00000 {
> + compatible = "mmio-sram";
> + reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
> +};
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index e83fdfe..4878507 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -510,6 +510,15 @@ 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 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 35a1463..08e2007 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -52,3 +52,4 @@ obj-$(CONFIG_INTEL_MEI) += mei/
> obj-$(CONFIG_MAX8997_MUIC) += max8997-muic.o
> 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 0000000..7858c62
> --- /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,
> +};
> +
> +int __init sram_init(void)
> +{
> + return platform_driver_register(&sram_driver);
> +}
> +
> +postcore_initcall(sram_init);
> --
> 1.7.10.4
Tested on xilinx-zynq with OCM.
Tested-by: Michal Simek <monstr@...str.eu>
Thanks,
Michal
--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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