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author | Shawn Guo <shawn.guo@linaro.org> | 2012-04-29 00:02:34 +0800 |
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committer | Shawn Guo <shawn.guo@linaro.org> | 2012-05-09 00:02:35 +0800 |
commit | 23b5e15a2994fb0c1444f92b76f09a482f32843c (patch) | |
tree | 54695e5b39977bd1ed04dfd945c9052a85b57e0f /drivers/clk/mxs/clk-ref.c | |
parent | d48b97b403d23f6df0b990cee652bdf9a52337a3 (diff) | |
download | op-kernel-dev-23b5e15a2994fb0c1444f92b76f09a482f32843c.zip op-kernel-dev-23b5e15a2994fb0c1444f92b76f09a482f32843c.tar.gz |
clk: mxs: add mxs specific clocks
Add mxs specific clocks, pll, reference clock (PFD), integer divider
and fractional divider.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Diffstat (limited to 'drivers/clk/mxs/clk-ref.c')
-rw-r--r-- | drivers/clk/mxs/clk-ref.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/drivers/clk/mxs/clk-ref.c b/drivers/clk/mxs/clk-ref.c new file mode 100644 index 0000000..4adeed6 --- /dev/null +++ b/drivers/clk/mxs/clk-ref.c @@ -0,0 +1,154 @@ +/* + * Copyright 2012 Freescale Semiconductor, Inc. + * + * The code contained herein is licensed under the GNU General Public + * License. You may obtain a copy of the GNU General Public License + * Version 2 or later at the following locations: + * + * http://www.opensource.org/licenses/gpl-license.html + * http://www.gnu.org/copyleft/gpl.html + */ + +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/slab.h> +#include "clk.h" + +/** + * struct clk_ref - mxs reference clock + * @hw: clk_hw for the reference clock + * @reg: register address + * @idx: the index of the reference clock within the same register + * + * The mxs reference clock sources from pll. Every 4 reference clocks share + * one register space, and @idx is used to identify them. Each reference + * clock has a gate control and a fractional * divider. The rate is calculated + * as pll rate * (18 / FRAC), where FRAC = 18 ~ 35. + */ +struct clk_ref { + struct clk_hw hw; + void __iomem *reg; + u8 idx; +}; + +#define to_clk_ref(_hw) container_of(_hw, struct clk_ref, hw) + +static int clk_ref_enable(struct clk_hw *hw) +{ + struct clk_ref *ref = to_clk_ref(hw); + + writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + CLR); + + return 0; +} + +static void clk_ref_disable(struct clk_hw *hw) +{ + struct clk_ref *ref = to_clk_ref(hw); + + writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + SET); +} + +static unsigned long clk_ref_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_ref *ref = to_clk_ref(hw); + u64 tmp = parent_rate; + u8 frac = (readl_relaxed(ref->reg) >> (ref->idx * 8)) & 0x3f; + + tmp *= 18; + do_div(tmp, frac); + + return tmp; +} + +static long clk_ref_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + unsigned long parent_rate = *prate; + u64 tmp = parent_rate; + u8 frac; + + tmp = tmp * 18 + rate / 2; + do_div(tmp, rate); + frac = tmp; + + if (frac < 18) + frac = 18; + else if (frac > 35) + frac = 35; + + tmp = parent_rate; + tmp *= 18; + do_div(tmp, frac); + + return tmp; +} + +static int clk_ref_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_ref *ref = to_clk_ref(hw); + unsigned long flags; + u64 tmp = parent_rate; + u32 val; + u8 frac, shift = ref->idx * 8; + + tmp = tmp * 18 + rate / 2; + do_div(tmp, rate); + frac = tmp; + + if (frac < 18) + frac = 18; + else if (frac > 35) + frac = 35; + + spin_lock_irqsave(&mxs_lock, flags); + + val = readl_relaxed(ref->reg); + val &= ~(0x3f << shift); + val |= frac << shift; + writel_relaxed(val, ref->reg); + + spin_unlock_irqrestore(&mxs_lock, flags); + + return 0; +} + +static const struct clk_ops clk_ref_ops = { + .enable = clk_ref_enable, + .disable = clk_ref_disable, + .recalc_rate = clk_ref_recalc_rate, + .round_rate = clk_ref_round_rate, + .set_rate = clk_ref_set_rate, +}; + +struct clk *mxs_clk_ref(const char *name, const char *parent_name, + void __iomem *reg, u8 idx) +{ + struct clk_ref *ref; + struct clk *clk; + struct clk_init_data init; + + ref = kzalloc(sizeof(*ref), GFP_KERNEL); + if (!ref) + return ERR_PTR(-ENOMEM); + + init.name = name; + init.ops = &clk_ref_ops; + init.flags = 0; + init.parent_names = (parent_name ? &parent_name: NULL); + init.num_parents = (parent_name ? 1 : 0); + + ref->reg = reg; + ref->idx = idx; + ref->hw.init = &init; + + clk = clk_register(NULL, &ref->hw); + if (IS_ERR(clk)) + kfree(ref); + + return clk; +} |