/*
   * Copyright (c) 2013 Samsung Electronics Co., Ltd.
   * Copyright (c) 2013 Linaro Ltd.
   * Author: Thomas Abraham <thomas.ab@samsung.com>
   *
   * 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.
   *
   * This file includes utility functions to register clocks to common
   * clock framework for Samsung platforms.
  */
  
  #include <linux/slab.h>
  #include <linux/clkdev.h>
  #include <linux/clk.h>
  #include <linux/clk-provider.h>
  #include <linux/of_address.h>
  #include <linux/syscore_ops.h>
  
  #include "clk.h"
  
  static LIST_HEAD(clock_reg_cache_list);
  
  void samsung_clk_save(void __iomem *base,
  				    struct samsung_clk_reg_dump *rd,
  				    unsigned int num_regs)
  {
  	for (; num_regs > 0; --num_regs, ++rd)
  		rd->value = readl(base + rd->offset);
  }
  
  void samsung_clk_restore(void __iomem *base,
  				      const struct samsung_clk_reg_dump *rd,
  				      unsigned int num_regs)
  {
  	for (; num_regs > 0; --num_regs, ++rd)
  		writel(rd->value, base + rd->offset);
  }
  
  struct samsung_clk_reg_dump *samsung_clk_alloc_reg_dump(
  						const unsigned long *rdump,
  						unsigned long nr_rdump)
  {
  	struct samsung_clk_reg_dump *rd;
  	unsigned int i;
  
  	rd = kcalloc(nr_rdump, sizeof(*rd), GFP_KERNEL);
  	if (!rd)
  		return NULL;
  
  	for (i = 0; i < nr_rdump; ++i)
  		rd[i].offset = rdump[i];
  
  	return rd;
  }
  
  /* setup the essentials required to support clock lookup using ccf */
  struct samsung_clk_provider *__init samsung_clk_init(struct device_node *np,
  			void __iomem *base, unsigned long nr_clks)
  {
  	struct samsung_clk_provider *ctx;
  	struct clk **clk_table;
  	int i;
  
  	ctx = kzalloc(sizeof(struct samsung_clk_provider), GFP_KERNEL);
  	if (!ctx)
  		panic("could not allocate clock provider context.
  ");
  
  	clk_table = kcalloc(nr_clks, sizeof(struct clk *), GFP_KERNEL);
  	if (!clk_table)
  		panic("could not allocate clock lookup table
  ");
  
  	for (i = 0; i < nr_clks; ++i)
  		clk_table[i] = ERR_PTR(-ENOENT);
  
  	ctx->reg_base = base;
  	ctx->clk_data.clks = clk_table;
  	ctx->clk_data.clk_num = nr_clks;
  	spin_lock_init(&ctx->lock);
  
  	return ctx;
  }
  
  void __init samsung_clk_of_add_provider(struct device_node *np,
  				struct samsung_clk_provider *ctx)
  {
  	if (np) {
  		if (of_clk_add_provider(np, of_clk_src_onecell_get,
  					&ctx->clk_data))
  			panic("could not register clk provider
  ");
  	}
  }
  
  /* add a clock instance to the clock lookup table used for dt based lookup */
  void samsung_clk_add_lookup(struct samsung_clk_provider *ctx, struct clk *clk,
  				unsigned int id)
  {
  	if (ctx->clk_data.clks && id)
  		ctx->clk_data.clks[id] = clk;
  }
  
  /* register a list of aliases */
  void __init samsung_clk_register_alias(struct samsung_clk_provider *ctx,
  				const struct samsung_clock_alias *list,
  				unsigned int nr_clk)
  {
  	struct clk *clk;
  	unsigned int idx, ret;
  
  	if (!ctx->clk_data.clks) {
  		pr_err("%s: clock table missing
  ", __func__);
  		return;
  	}
  
  	for (idx = 0; idx < nr_clk; idx++, list++) {
  		if (!list->id) {
  			pr_err("%s: clock id missing for index %d
  ", __func__,
  				idx);
  			continue;
  		}
  
  		clk = ctx->clk_data.clks[list->id];
  		if (!clk) {
  			pr_err("%s: failed to find clock %d
  ", __func__,
  				list->id);
  			continue;
  		}
  
  		ret = clk_register_clkdev(clk, list->alias, list->dev_name);
  		if (ret)
  			pr_err("%s: failed to register lookup %s
  ",
  					__func__, list->alias);
  	}
  }
  
  /* register a list of fixed clocks */
  void __init samsung_clk_register_fixed_rate(struct samsung_clk_provider *ctx,
  		const struct samsung_fixed_rate_clock *list,
  		unsigned int nr_clk)
  {
  	struct clk *clk;
  	unsigned int idx, ret;
  
  	for (idx = 0; idx < nr_clk; idx++, list++) {
  		clk = clk_register_fixed_rate(NULL, list->name,
  			list->parent_name, list->flags, list->fixed_rate);
  		if (IS_ERR(clk)) {
  			pr_err("%s: failed to register clock %s
  ", __func__,
  				list->name);
  			continue;
  		}
  
  		samsung_clk_add_lookup(ctx, clk, list->id);
  
  		/*
  		 * Unconditionally add a clock lookup for the fixed rate clocks.
  		 * There are not many of these on any of Samsung platforms.
  		 */
  		ret = clk_register_clkdev(clk, list->name, NULL);
  		if (ret)
  			pr_err("%s: failed to register clock lookup for %s",
  				__func__, list->name);
  	}
  }
  
  /* register a list of fixed factor clocks */
  void __init samsung_clk_register_fixed_factor(struct samsung_clk_provider *ctx,
  		const struct samsung_fixed_factor_clock *list, unsigned int nr_clk)
  {
  	struct clk *clk;
  	unsigned int idx;
  
  	for (idx = 0; idx < nr_clk; idx++, list++) {
  		clk = clk_register_fixed_factor(NULL, list->name,
  			list->parent_name, list->flags, list->mult, list->div);
  		if (IS_ERR(clk)) {
  			pr_err("%s: failed to register clock %s
  ", __func__,
  				list->name);
  			continue;
  		}
  
  		samsung_clk_add_lookup(ctx, clk, list->id);
  	}
  }
  
  /* register a list of mux clocks */
  void __init samsung_clk_register_mux(struct samsung_clk_provider *ctx,
  				const struct samsung_mux_clock *list,
  				unsigned int nr_clk)
  {
  	struct clk *clk;
  	unsigned int idx, ret;
  
  	for (idx = 0; idx < nr_clk; idx++, list++) {
  		clk = clk_register_mux(NULL, list->name, list->parent_names,
  			list->num_parents, list->flags,
  			ctx->reg_base + list->offset,
  			list->shift, list->width, list->mux_flags, &ctx->lock);
  		if (IS_ERR(clk)) {
  			pr_err("%s: failed to register clock %s
  ", __func__,
  				list->name);
  			continue;
  		}
  
  		samsung_clk_add_lookup(ctx, clk, list->id);
  
  		/* register a clock lookup only if a clock alias is specified */
  		if (list->alias) {
  			ret = clk_register_clkdev(clk, list->alias,
  						list->dev_name);
  			if (ret)
  				pr_err("%s: failed to register lookup %s
  ",
  						__func__, list->alias);
  		}
  	}
  }
  
  /* register a list of div clocks */
  void __init samsung_clk_register_div(struct samsung_clk_provider *ctx,
  				const struct samsung_div_clock *list,
  				unsigned int nr_clk)
  {
  	struct clk *clk;
  	unsigned int idx, ret;
  
  	for (idx = 0; idx < nr_clk; idx++, list++) {
  		if (list->table)
  			clk = clk_register_divider_table(NULL, list->name,
  				list->parent_name, list->flags,
  				ctx->reg_base + list->offset,
  				list->shift, list->width, list->div_flags,
  				list->table, &ctx->lock);
  		else
  			clk = clk_register_divider(NULL, list->name,
  				list->parent_name, list->flags,
  				ctx->reg_base + list->offset, list->shift,
  				list->width, list->div_flags, &ctx->lock);
  		if (IS_ERR(clk)) {
  			pr_err("%s: failed to register clock %s
  ", __func__,
  				list->name);
  			continue;
  		}
  
  		samsung_clk_add_lookup(ctx, clk, list->id);
  
  		/* register a clock lookup only if a clock alias is specified */
  		if (list->alias) {
  			ret = clk_register_clkdev(clk, list->alias,
  						list->dev_name);
  			if (ret)
  				pr_err("%s: failed to register lookup %s
  ",
  						__func__, list->alias);
  		}
  	}
  }
  
  /* register a list of gate clocks */
  void __init samsung_clk_register_gate(struct samsung_clk_provider *ctx,
  				const struct samsung_gate_clock *list,
  				unsigned int nr_clk)
  {
  	struct clk *clk;
  	unsigned int idx, ret;
  
  	for (idx = 0; idx < nr_clk; idx++, list++) {
  		clk = clk_register_gate(NULL, list->name, list->parent_name,
  				list->flags, ctx->reg_base + list->offset,
  				list->bit_idx, list->gate_flags, &ctx->lock);
  		if (IS_ERR(clk)) {
  			pr_err("%s: failed to register clock %s
  ", __func__,
  				list->name);
  			continue;
  		}
  
  		/* register a clock lookup only if a clock alias is specified */
  		if (list->alias) {
  			ret = clk_register_clkdev(clk, list->alias,
  							list->dev_name);
  			if (ret)
  				pr_err("%s: failed to register lookup %s
  ",
  					__func__, list->alias);
  		}
  
  		samsung_clk_add_lookup(ctx, clk, list->id);
  	}
  }
  
  /*
   * obtain the clock speed of all external fixed clock sources from device
   * tree and register it
   */
  void __init samsung_clk_of_register_fixed_ext(struct samsung_clk_provider *ctx,
  			struct samsung_fixed_rate_clock *fixed_rate_clk,
  			unsigned int nr_fixed_rate_clk,
  			const struct of_device_id *clk_matches)
  {
  	const struct of_device_id *match;
  	struct device_node *clk_np;
  	u32 freq;
  
  	for_each_matching_node_and_match(clk_np, clk_matches, &match) {
  		if (of_property_read_u32(clk_np, "clock-frequency", &freq))
  			continue;
  		fixed_rate_clk[(unsigned long)match->data].fixed_rate = freq;
  	}
  	samsung_clk_register_fixed_rate(ctx, fixed_rate_clk, nr_fixed_rate_clk);
  }
  
  /* utility function to get the rate of a specified clock */
  unsigned long _get_rate(const char *clk_name)
  {
  	struct clk *clk;
  
  	clk = __clk_lookup(clk_name);
  	if (!clk) {
  		pr_err("%s: could not find clock %s
  ", __func__, clk_name);
  		return 0;
  	}
  
  	return clk_get_rate(clk);
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int samsung_clk_suspend(void)
  {
  	struct samsung_clock_reg_cache *reg_cache;
  
  	list_for_each_entry(reg_cache, &clock_reg_cache_list, node)
  		samsung_clk_save(reg_cache->reg_base, reg_cache->rdump,
  				reg_cache->rd_num);
  	return 0;
  }
  
  static void samsung_clk_resume(void)
  {
  	struct samsung_clock_reg_cache *reg_cache;
  
  	list_for_each_entry(reg_cache, &clock_reg_cache_list, node)
  		samsung_clk_restore(reg_cache->reg_base, reg_cache->rdump,
  				reg_cache->rd_num);
  }
  
  static struct syscore_ops samsung_clk_syscore_ops = {
  	.suspend = samsung_clk_suspend,
  	.resume = samsung_clk_resume,
  };
  
  static void samsung_clk_sleep_init(void __iomem *reg_base,
  		const unsigned long *rdump,
  		unsigned long nr_rdump)
  {
  	struct samsung_clock_reg_cache *reg_cache;
  
  	reg_cache = kzalloc(sizeof(struct samsung_clock_reg_cache),
  			GFP_KERNEL);
  	if (!reg_cache)
  		panic("could not allocate register reg_cache.
  ");
  	reg_cache->rdump = samsung_clk_alloc_reg_dump(rdump, nr_rdump);
  
  	if (!reg_cache->rdump)
  		panic("could not allocate register dump storage.
  ");
  
  	if (list_empty(&clock_reg_cache_list))
  		register_syscore_ops(&samsung_clk_syscore_ops);
  
  	reg_cache->reg_base = reg_base;
  	reg_cache->rd_num = nr_rdump;
  	list_add_tail(&reg_cache->node, &clock_reg_cache_list);
  }
  
  #else
  static void samsung_clk_sleep_init(void __iomem *reg_base,
  		const unsigned long *rdump,
  		unsigned long nr_rdump) {}
  #endif
  
  /*
   * Common function which registers plls, muxes, dividers and gates
   * for each CMU. It also add CMU register list to register cache.
   */
  struct samsung_clk_provider * __init samsung_cmu_register_one(
  			struct device_node *np,
  			struct samsung_cmu_info *cmu)
  {
  	void __iomem *reg_base;
  	struct samsung_clk_provider *ctx;
  
  	reg_base = of_iomap(np, 0);
  	if (!reg_base) {
  		panic("%s: failed to map registers
  ", __func__);
  		return NULL;
  	}
  
  	ctx = samsung_clk_init(np, reg_base, cmu->nr_clk_ids);
  	if (!ctx) {
  		panic("%s: unable to allocate ctx
  ", __func__);
  		return ctx;
  	}
  
  	if (cmu->pll_clks)
  		samsung_clk_register_pll(ctx, cmu->pll_clks, cmu->nr_pll_clks,
  			reg_base);
  	if (cmu->mux_clks)
  		samsung_clk_register_mux(ctx, cmu->mux_clks,
  			cmu->nr_mux_clks);
  	if (cmu->div_clks)
  		samsung_clk_register_div(ctx, cmu->div_clks, cmu->nr_div_clks);
  	if (cmu->gate_clks)
  		samsung_clk_register_gate(ctx, cmu->gate_clks,
  			cmu->nr_gate_clks);
  	if (cmu->fixed_clks)
  		samsung_clk_register_fixed_rate(ctx, cmu->fixed_clks,
  			cmu->nr_fixed_clks);
  	if (cmu->fixed_factor_clks)
  		samsung_clk_register_fixed_factor(ctx, cmu->fixed_factor_clks,
  			cmu->nr_fixed_factor_clks);
  	if (cmu->clk_regs)
  		samsung_clk_sleep_init(reg_base, cmu->clk_regs,
  			cmu->nr_clk_regs);
  
  	samsung_clk_of_add_provider(np, ctx);
  
  	return ctx;
  }