diff options
| -rw-r--r-- | drivers/clk/Makefile | 3 | ||||
| -rw-r--r-- | drivers/clk/clk-fractional-divider.c | 152 | ||||
| -rw-r--r-- | include/linux/clk.h | 9 |
3 files changed, 163 insertions, 1 deletions
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index 9df98c8716..47ed7b1b6e 100644 --- a/drivers/clk/Makefile +++ b/drivers/clk/Makefile @@ -1,5 +1,6 @@ obj-$(CONFIG_COMMON_CLK) += clk.o clk-fixed.o clk-divider.o clk-fixed-factor.o \ - clk-mux.o clk-gate.o clk-composite.o + clk-mux.o clk-gate.o clk-composite.o \ + clk-fractional-divider.o obj-$(CONFIG_CLKDEV_LOOKUP) += clkdev.o obj-$(CONFIG_ARCH_MVEBU) += mvebu/ diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c new file mode 100644 index 0000000000..59b98aac9e --- /dev/null +++ b/drivers/clk/clk-fractional-divider.c @@ -0,0 +1,152 @@ +/* + * Copyright (C) 2014 Intel Corporation + * + * 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 fractional divider clock implementation. + * Output rate = (m / n) * parent_rate. + */ + +#include <common.h> +#include <io.h> +#include <malloc.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/gcd.h> +#include <linux/math64.h> +#include <linux/barebox-wrapper.h> + +#define to_clk_fd(_hw) container_of(_hw, struct clk_fractional_divider, clk) + +struct clk_fractional_divider { + struct clk clk; + void __iomem *reg; + u8 mshift; + u32 mmask; + u8 nshift; + u32 nmask; + u8 flags; +}; + +static unsigned long clk_fd_recalc_rate(struct clk *hw, + unsigned long parent_rate) +{ + struct clk_fractional_divider *fd = to_clk_fd(hw); + u32 val, m, n; + u64 ret; + + val = readl(fd->reg); + + m = (val & fd->mmask) >> fd->mshift; + n = (val & fd->nmask) >> fd->nshift; + + ret = (u64)parent_rate * m; + do_div(ret, n); + + return ret; +} + +static long clk_fd_round_rate(struct clk *hw, unsigned long rate, + unsigned long *prate) +{ + struct clk_fractional_divider *fd = to_clk_fd(hw); + unsigned maxn = (fd->nmask >> fd->nshift) + 1; + unsigned div; + + if (!rate || rate >= *prate) + return *prate; + + div = gcd(*prate, rate); + + while ((*prate / div) > maxn) { + div <<= 1; + rate <<= 1; + } + + return rate; +} + +static int clk_fd_set_rate(struct clk *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_fractional_divider *fd = to_clk_fd(hw); + unsigned long div; + unsigned n, m; + u32 val; + + div = gcd(parent_rate, rate); + m = rate / div; + n = parent_rate / div; + + val = readl(fd->reg); + val &= ~(fd->mmask | fd->nmask); + val |= (m << fd->mshift) | (n << fd->nshift); + writel(val, fd->reg); + + return 0; +} + +const struct clk_ops clk_fractional_divider_ops = { + .recalc_rate = clk_fd_recalc_rate, + .round_rate = clk_fd_round_rate, + .set_rate = clk_fd_set_rate, +}; +EXPORT_SYMBOL_GPL(clk_fractional_divider_ops); + +struct clk *clk_fractional_divider_alloc( + const char *name, const char *parent_name, unsigned long flags, + void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth, + u8 clk_divider_flags) +{ + struct clk_fractional_divider *fd; + + fd = xzalloc(sizeof(*fd)); + + fd->reg = reg; + fd->mshift = mshift; + fd->mmask = (BIT(mwidth) - 1) << mshift; + fd->nshift = nshift; + fd->nmask = (BIT(nwidth) - 1) << nshift; + fd->flags = clk_divider_flags; + fd->clk.name = name; + fd->clk.ops = &clk_fractional_divider_ops; + fd->clk.flags = flags; + fd->clk.parent_names = parent_name ? &parent_name : NULL; + fd->clk.num_parents = parent_name ? 1 : 0; + + return &fd->clk; +} + +void clk_fractional_divider_free(struct clk *clk_fd) +{ + struct clk_fractional_divider *fd = to_clk_fd(clk_fd); + + free(fd); +} + +struct clk *clk_fractional_divider( + const char *name, const char *parent_name, unsigned long flags, + void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth, + u8 clk_divider_flags) +{ + struct clk *fd; + int ret; + + fd = clk_fractional_divider_alloc(name, parent_name, flags, + reg, mshift, mwidth, nshift, nwidth, + clk_divider_flags); + + if (IS_ERR(fd)) + return fd; + + ret = clk_register(fd); + if (ret) { + clk_fractional_divider_free(fd); + return ERR_PTR(ret); + } + + return fd; +} +EXPORT_SYMBOL_GPL(clk_register_fractional_divider); diff --git a/include/linux/clk.h b/include/linux/clk.h index fe8ae5cc1e..de2d4a5d8a 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -260,6 +260,15 @@ struct clk *clk_divider_table(const char *name, struct clk *clk_fixed_factor(const char *name, const char *parent, unsigned int mult, unsigned int div, unsigned flags); +struct clk *clk_fractional_divider_alloc( + const char *name, const char *parent_name, unsigned long flags, + void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth, + u8 clk_divider_flags); +struct clk *clk_fractional_divider( + const char *name, const char *parent_name, unsigned long flags, + void __iomem *reg, u8 mshift, u8 mwidth, u8 nshift, u8 nwidth, + u8 clk_divider_flags); +void clk_fractional_divider_free(struct clk *clk_fd); struct clk *clk_mux_alloc(const char *name, void __iomem *reg, u8 shift, u8 width, const char **parents, u8 num_parents, |