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clock36xx.c

/*
 * OMAP36xx-specific clkops
 *
 * Copyright (C) 2010 Texas Instruments, Inc.
 * Copyright (C) 2010 Nokia Corporation
 *
 * Mike Turquette
 * Vijaykumar GN
 * Paul Walmsley
 *
 * Parts of this code are based on code written by
 * Richard Woodruff, Tony Lindgren, Tuukka Tikkanen, Karthik Dasu,
 * Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#undef DEBUG

#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/io.h>

#include <plat/clock.h>

#include "clock.h"
#include "clock36xx.h"


/**
 * omap36xx_pwrdn_clk_enable_with_hsdiv_restore - enable clocks suffering
 *         from HSDivider PWRDN problem Implements Errata ID: i556.
 * @clk: DPLL output struct clk
 *
 * 3630 only: dpll3_m3_ck, dpll4_m2_ck, dpll4_m3_ck, dpll4_m4_ck,
 * dpll4_m5_ck & dpll4_m6_ck dividers gets loaded with reset
 * valueafter their respective PWRDN bits are set.  Any dummy write
 * (Any other value different from the Read value) to the
 * corresponding CM_CLKSEL register will refresh the dividers.
 */
static int omap36xx_pwrdn_clk_enable_with_hsdiv_restore(struct clk *clk)
{
      u32 dummy_v, orig_v, clksel_shift;
      int ret;

      /* Clear PWRDN bit of HSDIVIDER */
      ret = omap2_dflt_clk_enable(clk);

      /* Restore the dividers */
      if (!ret) {
            clksel_shift = __ffs(clk->parent->clksel_mask);
            orig_v = __raw_readl(clk->parent->clksel_reg);
            dummy_v = orig_v;

            /* Write any other value different from the Read value */
            dummy_v ^= (1 << clksel_shift);
            __raw_writel(dummy_v, clk->parent->clksel_reg);

            /* Write the original divider */
            __raw_writel(orig_v, clk->parent->clksel_reg);
      }

      return ret;
}

const struct clkops clkops_omap36xx_pwrdn_with_hsdiv_wait_restore = {
      .enable           = omap36xx_pwrdn_clk_enable_with_hsdiv_restore,
      .disable    = omap2_dflt_clk_disable,
      .find_companion   = omap2_clk_dflt_find_companion,
      .find_idlest      = omap2_clk_dflt_find_idlest,
};

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