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    Subject[PATCH V2 1/3] lib: add support for stmp-style devices
    Date
    MX23/28 use IP cores which follow a register layout I have first seen on
    STMP3xxx SoCs. In this layout, every register actually has four u32:

    1.) to store a value directly
    2.) a SET register where every 1-bit sets the corresponding bit,
    others are unaffected
    3.) same with a CLR register
    4.) same with a TOG (toggle) register

    Also, the 2 MSBs in register 0 are always the same and can be used to reset
    the IP core.

    All this is strictly speaking not mach-specific (but IP core specific) and,
    thus, doesn't need to be in mach-mxs/include. At least, mx6 and mx50 also
    utilize IP cores following this stmp-style. So:

    Introduce a stmp-style device, put the code and defines for that in a public
    place (lib/), and let drivers for stmp-style devices select that code.
    To avoid regressions and ease reviewing, the actual code is simply copied from
    mach-mxs. It definately wants updates, but those need a seperate patch series.

    Voila, mach dependency gone, reusable code introduced. Note that I didn't
    remove the duplicated code from mach-mxs yet, first the drivers have to be
    converted.

    Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
    Acked-by: Shawn Guo <shawn.guo@linaro.org>
    ---
    include/linux/stmp_device.h | 20 +++++++++++
    lib/Kconfig | 3 ++
    lib/Makefile | 2 +
    lib/stmp_device.c | 80 +++++++++++++++++++++++++++++++++++++++++++
    4 files changed, 105 insertions(+), 0 deletions(-)
    create mode 100644 include/linux/stmp_device.h
    create mode 100644 lib/stmp_device.c

    diff --git a/include/linux/stmp_device.h b/include/linux/stmp_device.h
    new file mode 100644
    index 0000000..6cf7ec9
    --- /dev/null
    +++ b/include/linux/stmp_device.h
    @@ -0,0 +1,20 @@
    +/*
    + * basic functions for devices following the "stmp" style register layout
    + *
    + * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
    + *
    + * 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.
    + */
    +
    +#ifndef __STMP_DEVICE_H__
    +#define __STMP_DEVICE_H__
    +
    +#define STMP_OFFSET_REG_SET 0x4
    +#define STMP_OFFSET_REG_CLR 0x8
    +#define STMP_OFFSET_REG_TOG 0xc
    +
    +extern int stmp_reset_block(void __iomem *);
    +#endif /* __STMP_DEVICE_H__ */
    diff --git a/lib/Kconfig b/lib/Kconfig
    index 028aba9..d4af46f 100644
    --- a/lib/Kconfig
    +++ b/lib/Kconfig
    @@ -29,6 +29,9 @@ config GENERIC_IOMAP
    bool
    select GENERIC_PCI_IOMAP

    +config STMP_DEVICE
    + bool
    +
    config CRC_CCITT
    tristate "CRC-CCITT functions"
    help
    diff --git a/lib/Makefile b/lib/Makefile
    index 18515f0..f78dbcd 100644
    --- a/lib/Makefile
    +++ b/lib/Makefile
    @@ -123,6 +123,8 @@ obj-$(CONFIG_SIGNATURE) += digsig.o

    obj-$(CONFIG_CLZ_TAB) += clz_tab.o

    +obj-$(CONFIG_STMP_DEVICE) += stmp_device.o
    +
    hostprogs-y := gen_crc32table
    clean-files := crc32table.h

    diff --git a/lib/stmp_device.c b/lib/stmp_device.c
    new file mode 100644
    index 0000000..8ac9bcc
    --- /dev/null
    +++ b/lib/stmp_device.c
    @@ -0,0 +1,80 @@
    +/*
    + * Copyright (C) 1999 ARM Limited
    + * Copyright (C) 2000 Deep Blue Solutions Ltd
    + * Copyright 2006-2007,2010 Freescale Semiconductor, Inc. All Rights Reserved.
    + * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
    + * Copyright 2009 Ilya Yanok, Emcraft Systems Ltd, yanok@emcraft.com
    + * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K.
    + *
    + * 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.
    + */
    +
    +#include <linux/io.h>
    +#include <linux/errno.h>
    +#include <linux/delay.h>
    +#include <linux/module.h>
    +#include <linux/stmp_device.h>
    +
    +#define STMP_MODULE_CLKGATE (1 << 30)
    +#define STMP_MODULE_SFTRST (1 << 31)
    +
    +/*
    + * Clear the bit and poll it cleared. This is usually called with
    + * a reset address and mask being either SFTRST(bit 31) or CLKGATE
    + * (bit 30).
    + */
    +static int stmp_clear_poll_bit(void __iomem *addr, u32 mask)
    +{
    + int timeout = 0x400;
    +
    + writel(mask, addr + STMP_OFFSET_REG_CLR);
    + udelay(1);
    + while ((readl(addr) & mask) && --timeout)
    + /* nothing */;
    +
    + return !timeout;
    +}
    +
    +int stmp_reset_block(void __iomem *reset_addr)
    +{
    + int ret;
    + int timeout = 0x400;
    +
    + /* clear and poll SFTRST */
    + ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
    + if (unlikely(ret))
    + goto error;
    +
    + /* clear CLKGATE */
    + writel(STMP_MODULE_CLKGATE, reset_addr + STMP_OFFSET_REG_CLR);
    +
    + /* set SFTRST to reset the block */
    + writel(STMP_MODULE_SFTRST, reset_addr + STMP_OFFSET_REG_SET);
    + udelay(1);
    +
    + /* poll CLKGATE becoming set */
    + while ((!(readl(reset_addr) & STMP_MODULE_CLKGATE)) && --timeout)
    + /* nothing */;
    + if (unlikely(!timeout))
    + goto error;
    +
    + /* clear and poll SFTRST */
    + ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST);
    + if (unlikely(ret))
    + goto error;
    +
    + /* clear and poll CLKGATE */
    + ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_CLKGATE);
    + if (unlikely(ret))
    + goto error;
    +
    + return 0;
    +
    +error:
    + pr_err("%s(%p): module reset timeout\n", __func__, reset_addr);
    + return -ETIMEDOUT;
    +}
    +EXPORT_SYMBOL(stmp_reset_block);
    --
    1.7.2.5


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