140 lines
3.2 KiB
C
140 lines
3.2 KiB
C
/*
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* ocotp.c - barebox driver for the On-Chip One Time Programmable for MXS
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*
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* Copyright (C) 2012 by Wolfram Sang, Pengutronix e.K.
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* based on the kernel driver which is
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* Copyright 2010 Freescale Semiconductor, Inc. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <common.h>
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#include <init.h>
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#include <driver.h>
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#include <xfuncs.h>
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#include <errno.h>
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#include <param.h>
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#include <fcntl.h>
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#include <malloc.h>
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#include <io.h>
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#include <clock.h>
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#include <mach/generic.h>
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#include <mach/ocotp.h>
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#include <mach/imx-regs.h>
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#define DRIVERNAME "ocotp"
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#define OCOTP_WORD_OFFSET 0x20
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#define BM_OCOTP_CTRL_BUSY (1 << 8)
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#define BM_OCOTP_CTRL_ERROR (1 << 9)
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#define BM_OCOTP_CTRL_RD_BANK_OPEN (1 << 12)
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struct ocotp_priv {
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struct cdev cdev;
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void __iomem *base;
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};
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static ssize_t mxs_ocotp_cdev_read(struct cdev *cdev, void *buf, size_t count,
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loff_t offset, ulong flags)
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{
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struct ocotp_priv *priv = cdev->priv;
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void __iomem *base = priv->base;
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size_t size = min((loff_t)count, cdev->size - offset);
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uint64_t start;
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int i;
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/*
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* clk_enable(hbus_clk) for ocotp can be skipped
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* as it must be on when system is running.
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*/
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/* try to clear ERROR bit */
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writel(BM_OCOTP_CTRL_ERROR, base + BIT_CLR);
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/* check both BUSY and ERROR cleared */
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start = get_time_ns();
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while (readl(base) & (BM_OCOTP_CTRL_BUSY | BM_OCOTP_CTRL_ERROR))
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if (is_timeout(start, MSECOND))
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return -ETIMEDOUT;
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/* open OCOTP banks for read */
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writel(BM_OCOTP_CTRL_RD_BANK_OPEN, base + BIT_SET);
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/* approximately wait 32 hclk cycles */
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udelay(1);
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/* poll BUSY bit becoming cleared */
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start = get_time_ns();
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while (readl(base) & BM_OCOTP_CTRL_BUSY)
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if (is_timeout(start, MSECOND))
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return -ETIMEDOUT;
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for (i = 0; i < size; i++)
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/* When reading bytewise, we need to hop over the SET/CLR/TGL regs */
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((u8 *)buf)[i] = readb(base + OCOTP_WORD_OFFSET +
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(((i + offset) & 0xfc) << 2) + ((i + offset) & 3));
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/* close banks for power saving */
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writel(BM_OCOTP_CTRL_RD_BANK_OPEN, base + BIT_CLR);
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return size;
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}
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static struct file_operations mxs_ocotp_ops = {
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.read = mxs_ocotp_cdev_read,
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.lseek = dev_lseek_default,
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};
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static int mxs_ocotp_probe(struct device_d *dev)
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{
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int err;
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struct ocotp_priv *priv = xzalloc(sizeof (*priv));
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priv->base = dev_request_mem_region(dev, 0);
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priv->cdev.dev = dev;
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priv->cdev.ops = &mxs_ocotp_ops;
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priv->cdev.priv = priv;
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priv->cdev.size = cpu_is_mx23() ? 128 : 160;
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priv->cdev.name = DRIVERNAME;
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err = devfs_create(&priv->cdev);
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if (err < 0)
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return err;
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return 0;
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}
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static struct driver_d mxs_ocotp_driver = {
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.name = DRIVERNAME,
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.probe = mxs_ocotp_probe,
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};
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static int mxs_ocotp_init(void)
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{
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register_driver(&mxs_ocotp_driver);
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return 0;
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}
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coredevice_initcall(mxs_ocotp_init);
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int mxs_ocotp_read(void *buf, int count, int offset)
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{
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struct cdev *cdev;
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int ret;
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cdev = cdev_open(DRIVERNAME, O_RDONLY);
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if (!cdev)
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return -ENODEV;
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ret = cdev_read(cdev, buf, count, offset, 0);
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cdev_close(cdev);
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return ret;
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}
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