sram.c

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/*
 * SDK7786 FPGA SRAM Support.
 *
 * Copyright (C) 2010  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/string.h>
#include <mach/fpga.h>
#include <asm/sram.h>
#include <asm/sizes.h>

static int __init fpga_sram_init(void)
{
    unsigned long phys;
    unsigned int area;
    void __iomem *vaddr;
    int ret;
    u16 data;

    /* Enable FPGA SRAM */
    data = fpga_read_reg(LCLASR);
    data |= LCLASR_FRAMEN;
    fpga_write_reg(data, LCLASR);

    /*
     * FPGA_SEL determines the area mapping
     */
    area = (data & LCLASR_FPGA_SEL_MASK) >> LCLASR_FPGA_SEL_SHIFT;
    if (unlikely(area == LCLASR_AREA_MASK)) {
        pr_err("FPGA memory unmapped.\n");
        return -ENXIO;
    }

    /*
     * The memory itself occupies a 2KiB range at the top of the area
     * immediately below the system registers.
     */
    phys = (area << 26) + SZ_64M - SZ_4K;

    /*
     * The FPGA SRAM resides in translatable physical space, so set
     * up a mapping prior to inserting it in to the pool.
     */
    vaddr = ioremap(phys, SZ_2K);
    if (unlikely(!vaddr)) {
        pr_err("Failed remapping FPGA memory.\n");
        return -ENXIO;
    }

    pr_info("Adding %dKiB of FPGA memory at 0x%08lx-0x%08lx "
        "(area %d) to pool.\n",
        SZ_2K >> 10, phys, phys + SZ_2K - 1, area);

    ret = gen_pool_add(sram_pool, (unsigned long)vaddr, SZ_2K, -1);
    if (unlikely(ret < 0)) {
        pr_err("Failed adding memory\n");
        iounmap(vaddr);
        return ret;
    }

    return 0;
}
postcore_initcall(fpga_sram_init);