diff options
Diffstat (limited to 'drivers/clk/spear')
| -rw-r--r-- | drivers/clk/spear/Makefile | 2 | ||||
| -rw-r--r-- | drivers/clk/spear/clk-frac-synth.c | 165 | ||||
| -rw-r--r-- | drivers/clk/spear/clk.h | 16 |
3 files changed, 182 insertions, 1 deletions
diff --git a/drivers/clk/spear/Makefile b/drivers/clk/spear/Makefile index e36d8c66572..18270362219 100644 --- a/drivers/clk/spear/Makefile +++ b/drivers/clk/spear/Makefile @@ -2,4 +2,4 @@ # SPEAr Clock specific Makefile # -obj-y += clk.o clk-aux-synth.o clk-vco-pll.o +obj-y += clk.o clk-aux-synth.o clk-frac-synth.o clk-vco-pll.o diff --git a/drivers/clk/spear/clk-frac-synth.c b/drivers/clk/spear/clk-frac-synth.c new file mode 100644 index 00000000000..4dbdb3fe18e --- /dev/null +++ b/drivers/clk/spear/clk-frac-synth.c @@ -0,0 +1,165 @@ +/* + * Copyright (C) 2012 ST Microelectronics + * Viresh Kumar <viresh.kumar@st.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + * + * Fractional Synthesizer clock implementation + */ + +#define pr_fmt(fmt) "clk-frac-synth: " fmt + +#include <linux/clk-provider.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/err.h> +#include "clk.h" + +#define DIV_FACTOR_MASK 0x1FFFF + +/* + * DOC: Fractional Synthesizer clock + * + * Fout from synthesizer can be given from below equation: + * + * Fout= Fin/2*div (division factor) + * div is 17 bits:- + * 0-13 (fractional part) + * 14-16 (integer part) + * div is (16-14 bits).(13-0 bits) (in binary) + * + * Fout = Fin/(2 * div) + * Fout = ((Fin / 10000)/(2 * div)) * 10000 + * Fout = (2^14 * (Fin / 10000)/(2^14 * (2 * div))) * 10000 + * Fout = (((Fin / 10000) << 14)/(2 * (div << 14))) * 10000 + * + * div << 14 simply 17 bit value written at register. + * Max error due to scaling down by 10000 is 10 KHz + */ + +#define to_clk_frac(_hw) container_of(_hw, struct clk_frac, hw) + +static unsigned long frac_calc_rate(struct clk_hw *hw, unsigned long prate, + int index) +{ + struct clk_frac *frac = to_clk_frac(hw); + struct frac_rate_tbl *rtbl = frac->rtbl; + + prate /= 10000; + prate <<= 14; + prate /= (2 * rtbl[index].div); + prate *= 10000; + + return prate; +} + +static long clk_frac_round_rate(struct clk_hw *hw, unsigned long drate, + unsigned long *prate) +{ + struct clk_frac *frac = to_clk_frac(hw); + int unused; + + return clk_round_rate_index(hw, drate, *prate, frac_calc_rate, + frac->rtbl_cnt, &unused); +} + +static unsigned long clk_frac_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_frac *frac = to_clk_frac(hw); + unsigned long flags = 0; + unsigned int div = 1, val; + + if (frac->lock) + spin_lock_irqsave(frac->lock, flags); + + val = readl_relaxed(frac->reg); + + if (frac->lock) + spin_unlock_irqrestore(frac->lock, flags); + + div = val & DIV_FACTOR_MASK; + + if (!div) + return 0; + + parent_rate = parent_rate / 10000; + + parent_rate = (parent_rate << 14) / (2 * div); + return parent_rate * 10000; +} + +/* Configures new clock rate of frac */ +static int clk_frac_set_rate(struct clk_hw *hw, unsigned long drate, + unsigned long prate) +{ + struct clk_frac *frac = to_clk_frac(hw); + struct frac_rate_tbl *rtbl = frac->rtbl; + unsigned long flags = 0, val; + int i; + + clk_round_rate_index(hw, drate, prate, frac_calc_rate, frac->rtbl_cnt, + &i); + + if (frac->lock) + spin_lock_irqsave(frac->lock, flags); + + val = readl_relaxed(frac->reg) & ~DIV_FACTOR_MASK; + val |= rtbl[i].div & DIV_FACTOR_MASK; + writel_relaxed(val, frac->reg); + + if (frac->lock) + spin_unlock_irqrestore(frac->lock, flags); + + return 0; +} + +struct clk_ops clk_frac_ops = { + .recalc_rate = clk_frac_recalc_rate, + .round_rate = clk_frac_round_rate, + .set_rate = clk_frac_set_rate, +}; + +struct clk *clk_register_frac(const char *name, const char *parent_name, + unsigned long flags, void __iomem *reg, + struct frac_rate_tbl *rtbl, u8 rtbl_cnt, spinlock_t *lock) +{ + struct clk_init_data init; + struct clk_frac *frac; + struct clk *clk; + + if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) { + pr_err("Invalid arguments passed"); + return ERR_PTR(-EINVAL); + } + + frac = kzalloc(sizeof(*frac), GFP_KERNEL); + if (!frac) { + pr_err("could not allocate frac clk\n"); + return ERR_PTR(-ENOMEM); + } + + /* struct clk_frac assignments */ + frac->reg = reg; + frac->rtbl = rtbl; + frac->rtbl_cnt = rtbl_cnt; + frac->lock = lock; + frac->hw.init = &init; + + init.name = name; + init.ops = &clk_frac_ops; + init.flags = flags; + init.parent_names = &parent_name; + init.num_parents = 1; + + clk = clk_register(NULL, &frac->hw); + if (!IS_ERR_OR_NULL(clk)) + return clk; + + pr_err("clk register failed\n"); + kfree(frac); + + return NULL; +} diff --git a/drivers/clk/spear/clk.h b/drivers/clk/spear/clk.h index c2290800503..ac9030bbd6c 100644 --- a/drivers/clk/spear/clk.h +++ b/drivers/clk/spear/clk.h @@ -55,6 +55,19 @@ struct clk_aux { spinlock_t *lock; }; +/* Fractional Synth clk */ +struct frac_rate_tbl { + u32 div; +}; + +struct clk_frac { + struct clk_hw hw; + void __iomem *reg; + struct frac_rate_tbl *rtbl; + u8 rtbl_cnt; + spinlock_t *lock; +}; + /* VCO-PLL clk */ struct pll_rate_tbl { u8 mode; @@ -87,6 +100,9 @@ struct clk *clk_register_aux(const char *aux_name, const char *gate_name, const char *parent_name, unsigned long flags, void __iomem *reg, struct aux_clk_masks *masks, struct aux_rate_tbl *rtbl, u8 rtbl_cnt, spinlock_t *lock, struct clk **gate_clk); +struct clk *clk_register_frac(const char *name, const char *parent_name, + unsigned long flags, void __iomem *reg, + struct frac_rate_tbl *rtbl, u8 rtbl_cnt, spinlock_t *lock); struct clk *clk_register_vco_pll(const char *vco_name, const char *pll_name, const char *vco_gate_name, const char *parent_name, unsigned long flags, void __iomem *mode_reg, void __iomem |