diff options
author | Viresh Kumar <viresh.kumar@st.com> | 2012-04-11 12:34:23 (GMT) |
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committer | Arnd Bergmann <arnd@arndb.de> | 2012-05-12 19:19:27 (GMT) |
commit | a45896bd3a4b7beb571fa704efa7c2782b791093 (patch) | |
tree | abbcf23625304e123839af8af6e5ba278d20797e /drivers/clk/spear/clk-gpt-synth.c | |
parent | 270b9f421e66ee5d135c99ba1c2b883c7750ab6c (diff) | |
download | linux-fsl-qoriq-a45896bd3a4b7beb571fa704efa7c2782b791093.tar.xz |
SPEAr: clk: Add General Purpose Timer Synthesizer clock
All SPEAr SoC's contain GPT Synthesizers. Their Fout is derived from
following equations:
Fout= Fin/((2 ^ (N+1)) * (M+1))
This patch adds in support for this type of clock.
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Reviewed-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/spear/clk-gpt-synth.c')
-rw-r--r-- | drivers/clk/spear/clk-gpt-synth.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/drivers/clk/spear/clk-gpt-synth.c b/drivers/clk/spear/clk-gpt-synth.c new file mode 100644 index 0000000..b471c97 --- /dev/null +++ b/drivers/clk/spear/clk-gpt-synth.c @@ -0,0 +1,154 @@ +/* + * 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. + * + * General Purpose Timer Synthesizer clock implementation + */ + +#define pr_fmt(fmt) "clk-gpt-synth: " fmt + +#include <linux/clk-provider.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/err.h> +#include "clk.h" + +#define GPT_MSCALE_MASK 0xFFF +#define GPT_NSCALE_SHIFT 12 +#define GPT_NSCALE_MASK 0xF + +/* + * DOC: General Purpose Timer Synthesizer clock + * + * Calculates gpt synth clk rate for different values of mscale and nscale + * + * Fout= Fin/((2 ^ (N+1)) * (M+1)) + */ + +#define to_clk_gpt(_hw) container_of(_hw, struct clk_gpt, hw) + +static unsigned long gpt_calc_rate(struct clk_hw *hw, unsigned long prate, + int index) +{ + struct clk_gpt *gpt = to_clk_gpt(hw); + struct gpt_rate_tbl *rtbl = gpt->rtbl; + + prate /= ((1 << (rtbl[index].nscale + 1)) * (rtbl[index].mscale + 1)); + + return prate; +} + +static long clk_gpt_round_rate(struct clk_hw *hw, unsigned long drate, + unsigned long *prate) +{ + struct clk_gpt *gpt = to_clk_gpt(hw); + int unused; + + return clk_round_rate_index(hw, drate, *prate, gpt_calc_rate, + gpt->rtbl_cnt, &unused); +} + +static unsigned long clk_gpt_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_gpt *gpt = to_clk_gpt(hw); + unsigned long flags = 0; + unsigned int div = 1, val; + + if (gpt->lock) + spin_lock_irqsave(gpt->lock, flags); + + val = readl_relaxed(gpt->reg); + + if (gpt->lock) + spin_unlock_irqrestore(gpt->lock, flags); + + div += val & GPT_MSCALE_MASK; + div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1); + + if (!div) + return 0; + + return parent_rate / div; +} + +/* Configures new clock rate of gpt */ +static int clk_gpt_set_rate(struct clk_hw *hw, unsigned long drate, + unsigned long prate) +{ + struct clk_gpt *gpt = to_clk_gpt(hw); + struct gpt_rate_tbl *rtbl = gpt->rtbl; + unsigned long flags = 0, val; + int i; + + clk_round_rate_index(hw, drate, prate, gpt_calc_rate, gpt->rtbl_cnt, + &i); + + if (gpt->lock) + spin_lock_irqsave(gpt->lock, flags); + + val = readl(gpt->reg) & ~GPT_MSCALE_MASK; + val &= ~(GPT_NSCALE_MASK << GPT_NSCALE_SHIFT); + + val |= rtbl[i].mscale & GPT_MSCALE_MASK; + val |= (rtbl[i].nscale & GPT_NSCALE_MASK) << GPT_NSCALE_SHIFT; + + writel_relaxed(val, gpt->reg); + + if (gpt->lock) + spin_unlock_irqrestore(gpt->lock, flags); + + return 0; +} + +static struct clk_ops clk_gpt_ops = { + .recalc_rate = clk_gpt_recalc_rate, + .round_rate = clk_gpt_round_rate, + .set_rate = clk_gpt_set_rate, +}; + +struct clk *clk_register_gpt(const char *name, const char *parent_name, unsigned + long flags, void __iomem *reg, struct gpt_rate_tbl *rtbl, u8 + rtbl_cnt, spinlock_t *lock) +{ + struct clk_init_data init; + struct clk_gpt *gpt; + struct clk *clk; + + if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) { + pr_err("Invalid arguments passed"); + return ERR_PTR(-EINVAL); + } + + gpt = kzalloc(sizeof(*gpt), GFP_KERNEL); + if (!gpt) { + pr_err("could not allocate gpt clk\n"); + return ERR_PTR(-ENOMEM); + } + + /* struct clk_gpt assignments */ + gpt->reg = reg; + gpt->rtbl = rtbl; + gpt->rtbl_cnt = rtbl_cnt; + gpt->lock = lock; + gpt->hw.init = &init; + + init.name = name; + init.ops = &clk_gpt_ops; + init.flags = flags; + init.parent_names = &parent_name; + init.num_parents = 1; + + clk = clk_register(NULL, &gpt->hw); + if (!IS_ERR_OR_NULL(clk)) + return clk; + + pr_err("clk register failed\n"); + kfree(gpt); + + return NULL; +} |