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kernel/linux-imx6_3.14.28/drivers/clk/versatile/clk-icst.c 3.56 KB
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  /*
   * Driver for the ICST307 VCO clock found in the ARM Reference designs.
   * We wrap the custom interface from <asm/hardware/icst.h> into the generic
   * clock framework.
   *
   * Copyright (C) 2012 Linus Walleij
   *
   * 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.
   *
   * TODO: when all ARM reference designs are migrated to generic clocks, the
   * ICST clock code from the ARM tree should probably be merged into this
   * file.
   */
  #include <linux/clk.h>
  #include <linux/clkdev.h>
  #include <linux/err.h>
  #include <linux/clk-provider.h>
  #include <linux/io.h>
  
  #include "clk-icst.h"
  
  /**
   * struct clk_icst - ICST VCO clock wrapper
   * @hw: corresponding clock hardware entry
   * @vcoreg: VCO register address
   * @lockreg: VCO lock register address
   * @params: parameters for this ICST instance
   * @rate: current rate
   */
  struct clk_icst {
  	struct clk_hw hw;
  	void __iomem *vcoreg;
  	void __iomem *lockreg;
  	const struct icst_params *params;
  	unsigned long rate;
  };
  
  #define to_icst(_hw) container_of(_hw, struct clk_icst, hw)
  
  /**
   * vco_get() - get ICST VCO settings from a certain register
   * @vcoreg: register containing the VCO settings
   */
  static struct icst_vco vco_get(void __iomem *vcoreg)
  {
  	u32 val;
  	struct icst_vco vco;
  
  	val = readl(vcoreg);
  	vco.v = val & 0x1ff;
  	vco.r = (val >> 9) & 0x7f;
  	vco.s = (val >> 16) & 03;
  	return vco;
  }
  
  /**
   * vco_set() - commit changes to an ICST VCO
   * @locreg: register to poke to unlock the VCO for writing
   * @vcoreg: register containing the VCO settings
   * @vco: ICST VCO parameters to commit
   */
  static void vco_set(void __iomem *lockreg,
  			void __iomem *vcoreg,
  			struct icst_vco vco)
  {
  	u32 val;
  
  	val = readl(vcoreg) & ~0x7ffff;
  	val |= vco.v | (vco.r << 9) | (vco.s << 16);
  
  	/* This magic unlocks the VCO so it can be controlled */
  	writel(0xa05f, lockreg);
  	writel(val, vcoreg);
  	/* This locks the VCO again */
  	writel(0, lockreg);
  }
  
  
  static unsigned long icst_recalc_rate(struct clk_hw *hw,
  				      unsigned long parent_rate)
  {
  	struct clk_icst *icst = to_icst(hw);
  	struct icst_vco vco;
  
  	vco = vco_get(icst->vcoreg);
  	icst->rate = icst_hz(icst->params, vco);
  	return icst->rate;
  }
  
  static long icst_round_rate(struct clk_hw *hw, unsigned long rate,
  			    unsigned long *prate)
  {
  	struct clk_icst *icst = to_icst(hw);
  	struct icst_vco vco;
  
  	vco = icst_hz_to_vco(icst->params, rate);
  	return icst_hz(icst->params, vco);
  }
  
  static int icst_set_rate(struct clk_hw *hw, unsigned long rate,
  			 unsigned long parent_rate)
  {
  	struct clk_icst *icst = to_icst(hw);
  	struct icst_vco vco;
  
  	vco = icst_hz_to_vco(icst->params, rate);
  	icst->rate = icst_hz(icst->params, vco);
  	vco_set(icst->lockreg, icst->vcoreg, vco);
  	return 0;
  }
  
  static const struct clk_ops icst_ops = {
  	.recalc_rate = icst_recalc_rate,
  	.round_rate = icst_round_rate,
  	.set_rate = icst_set_rate,
  };
  
  struct clk *icst_clk_register(struct device *dev,
  			const struct clk_icst_desc *desc,
  			const char *name,
  			void __iomem *base)
  {
  	struct clk *clk;
  	struct clk_icst *icst;
  	struct clk_init_data init;
  
  	icst = kzalloc(sizeof(struct clk_icst), GFP_KERNEL);
  	if (!icst) {
  		pr_err("could not allocate ICST clock!
  ");
  		return ERR_PTR(-ENOMEM);
  	}
  	init.name = name;
  	init.ops = &icst_ops;
  	init.flags = CLK_IS_ROOT;
  	init.parent_names = NULL;
  	init.num_parents = 0;
  	icst->hw.init = &init;
  	icst->params = desc->params;
  	icst->vcoreg = base + desc->vco_offset;
  	icst->lockreg = base + desc->lock_offset;
  
  	clk = clk_register(dev, &icst->hw);
  	if (IS_ERR(clk))
  		kfree(icst);
  
  	return clk;
  }