diff options
Diffstat (limited to 'drivers/clk/sunxi/clk-factors.c')
| -rw-r--r-- | drivers/clk/sunxi/clk-factors.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/drivers/clk/sunxi/clk-factors.c b/drivers/clk/sunxi/clk-factors.c new file mode 100644 index 000000000000..88523f91d9b7 --- /dev/null +++ b/drivers/clk/sunxi/clk-factors.c @@ -0,0 +1,180 @@ +/* + * Copyright (C) 2013 Emilio López <emilio@elopez.com.ar> + * + * 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. + * + * Adjustable factor-based clock implementation + */ + +#include <linux/clk-provider.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/err.h> +#include <linux/string.h> + +#include <linux/delay.h> + +#include "clk-factors.h" + +/* + * DOC: basic adjustable factor-based clock that cannot gate + * + * Traits of this clock: + * prepare - clk_prepare only ensures that parents are prepared + * enable - clk_enable only ensures that parents are enabled + * rate - rate is adjustable. + * clk->rate = (parent->rate * N * (K + 1) >> P) / (M + 1) + * parent - fixed parent. No clk_set_parent support + */ + +struct clk_factors { + struct clk_hw hw; + void __iomem *reg; + struct clk_factors_config *config; + void (*get_factors) (u32 *rate, u32 parent, u8 *n, u8 *k, u8 *m, u8 *p); + spinlock_t *lock; +}; + +#define to_clk_factors(_hw) container_of(_hw, struct clk_factors, hw) + +#define SETMASK(len, pos) (((-1U) >> (31-len)) << (pos)) +#define CLRMASK(len, pos) (~(SETMASK(len, pos))) +#define FACTOR_GET(bit, len, reg) (((reg) & SETMASK(len, bit)) >> (bit)) + +#define FACTOR_SET(bit, len, reg, val) \ + (((reg) & CLRMASK(len, bit)) | (val << (bit))) + +static unsigned long clk_factors_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + u8 n = 1, k = 0, p = 0, m = 0; + u32 reg; + unsigned long rate; + struct clk_factors *factors = to_clk_factors(hw); + struct clk_factors_config *config = factors->config; + + /* Fetch the register value */ + reg = readl(factors->reg); + + /* Get each individual factor if applicable */ + if (config->nwidth != SUNXI_FACTORS_NOT_APPLICABLE) + n = FACTOR_GET(config->nshift, config->nwidth, reg); + if (config->kwidth != SUNXI_FACTORS_NOT_APPLICABLE) + k = FACTOR_GET(config->kshift, config->kwidth, reg); + if (config->mwidth != SUNXI_FACTORS_NOT_APPLICABLE) + m = FACTOR_GET(config->mshift, config->mwidth, reg); + if (config->pwidth != SUNXI_FACTORS_NOT_APPLICABLE) + p = FACTOR_GET(config->pshift, config->pwidth, reg); + + /* Calculate the rate */ + rate = (parent_rate * n * (k + 1) >> p) / (m + 1); + + return rate; +} + +static long clk_factors_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + struct clk_factors *factors = to_clk_factors(hw); + factors->get_factors((u32 *)&rate, (u32)*parent_rate, + NULL, NULL, NULL, NULL); + + return rate; +} + +static int clk_factors_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + u8 n, k, m, p; + u32 reg; + struct clk_factors *factors = to_clk_factors(hw); + struct clk_factors_config *config = factors->config; + unsigned long flags = 0; + + factors->get_factors((u32 *)&rate, (u32)parent_rate, &n, &k, &m, &p); + + if (factors->lock) + spin_lock_irqsave(factors->lock, flags); + + /* Fetch the register value */ + reg = readl(factors->reg); + + /* Set up the new factors - macros do not do anything if width is 0 */ + reg = FACTOR_SET(config->nshift, config->nwidth, reg, n); + reg = FACTOR_SET(config->kshift, config->kwidth, reg, k); + reg = FACTOR_SET(config->mshift, config->mwidth, reg, m); + reg = FACTOR_SET(config->pshift, config->pwidth, reg, p); + + /* Apply them now */ + writel(reg, factors->reg); + + /* delay 500us so pll stabilizes */ + __delay((rate >> 20) * 500 / 2); + + if (factors->lock) + spin_unlock_irqrestore(factors->lock, flags); + + return 0; +} + +static const struct clk_ops clk_factors_ops = { + .recalc_rate = clk_factors_recalc_rate, + .round_rate = clk_factors_round_rate, + .set_rate = clk_factors_set_rate, +}; + +/** + * clk_register_factors - register a factors clock with + * the clock framework + * @dev: device registering this clock + * @name: name of this clock + * @parent_name: name of clock's parent + * @flags: framework-specific flags + * @reg: register address to adjust factors + * @config: shift and width of factors n, k, m and p + * @get_factors: function to calculate the factors for a given frequency + * @lock: shared register lock for this clock + */ +struct clk *clk_register_factors(struct device *dev, const char *name, + const char *parent_name, + unsigned long flags, void __iomem *reg, + struct clk_factors_config *config, + void (*get_factors)(u32 *rate, u32 parent, + u8 *n, u8 *k, u8 *m, u8 *p), + spinlock_t *lock) +{ + struct clk_factors *factors; + struct clk *clk; + struct clk_init_data init; + + /* allocate the factors */ + factors = kzalloc(sizeof(struct clk_factors), GFP_KERNEL); + if (!factors) { + pr_err("%s: could not allocate factors clk\n", __func__); + return ERR_PTR(-ENOMEM); + } + + init.name = name; + init.ops = &clk_factors_ops; + init.flags = flags; + init.parent_names = (parent_name ? &parent_name : NULL); + init.num_parents = (parent_name ? 1 : 0); + + /* struct clk_factors assignments */ + factors->reg = reg; + factors->config = config; + factors->lock = lock; + factors->hw.init = &init; + factors->get_factors = get_factors; + + /* register the clock */ + clk = clk_register(dev, &factors->hw); + + if (IS_ERR(clk)) + kfree(factors); + + return clk; +} |