From 4984c6f5e56c3e68922fd979347ba7aff385783b Mon Sep 17 00:00:00 2001 From: Philipp Zabel Date: Mon, 29 Apr 2013 16:17:12 -0700 Subject: misc: generic on-chip SRAM allocation driver 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. [akpm@linux-foundation.org: fix Kconfig text, make sram_init static] Signed-off-by: Philipp Zabel Reviewed-by: Shawn Guo Acked-by: Grant Likely Tested-by: Michal Simek Cc: Dong Aisheng Cc: Fabio Estevam Cc: Greg Kroah-Hartman Cc: Huang Shijie Cc: Javier Martin Cc: Matt Porter Cc: Michal Simek Cc: Paul Gortmaker Cc: Rob Herring Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds 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@5c000000 { + compatible = "mmio-sram"; + reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */ +}; diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index e29e798..3659d00 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 865cbc6..c235d5b 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 0000000..437192e --- /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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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); -- cgit v0.10.2