diff options
Diffstat (limited to 'drivers/clk/rockchip/clk-half-divider.c')
| -rw-r--r-- | drivers/clk/rockchip/clk-half-divider.c | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/drivers/clk/rockchip/clk-half-divider.c b/drivers/clk/rockchip/clk-half-divider.c new file mode 100644 index 000000000000..b8da6e799423 --- /dev/null +++ b/drivers/clk/rockchip/clk-half-divider.c @@ -0,0 +1,227 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2018 Fuzhou Rockchip Electronics Co., Ltd + */ + +#include <linux/slab.h> +#include <linux/clk-provider.h> +#include "clk.h" + +#define div_mask(width) ((1 << (width)) - 1) + +static bool _is_best_half_div(unsigned long rate, unsigned long now, + unsigned long best, unsigned long flags) +{ + if (flags & CLK_DIVIDER_ROUND_CLOSEST) + return abs(rate - now) < abs(rate - best); + + return now <= rate && now > best; +} + +static unsigned long clk_half_divider_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_divider *divider = to_clk_divider(hw); + unsigned int val; + + val = clk_readl(divider->reg) >> divider->shift; + val &= div_mask(divider->width); + val = val * 2 + 3; + + return DIV_ROUND_UP_ULL(((u64)parent_rate * 2), val); +} + +static int clk_half_divider_bestdiv(struct clk_hw *hw, unsigned long rate, + unsigned long *best_parent_rate, u8 width, + unsigned long flags) +{ + unsigned int i, bestdiv = 0; + unsigned long parent_rate, best = 0, now, maxdiv; + unsigned long parent_rate_saved = *best_parent_rate; + + if (!rate) + rate = 1; + + maxdiv = div_mask(width); + + if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) { + parent_rate = *best_parent_rate; + bestdiv = DIV_ROUND_UP_ULL(((u64)parent_rate * 2), rate); + if (bestdiv < 3) + bestdiv = 0; + else + bestdiv = (bestdiv - 3) / 2; + bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv; + return bestdiv; + } + + /* + * The maximum divider we can use without overflowing + * unsigned long in rate * i below + */ + maxdiv = min(ULONG_MAX / rate, maxdiv); + + for (i = 0; i <= maxdiv; i++) { + if (((u64)rate * (i * 2 + 3)) == ((u64)parent_rate_saved * 2)) { + /* + * It's the most ideal case if the requested rate can be + * divided from parent clock without needing to change + * parent rate, so return the divider immediately. + */ + *best_parent_rate = parent_rate_saved; + return i; + } + parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), + ((u64)rate * (i * 2 + 3)) / 2); + now = DIV_ROUND_UP_ULL(((u64)parent_rate * 2), + (i * 2 + 3)); + + if (_is_best_half_div(rate, now, best, flags)) { + bestdiv = i; + best = now; + *best_parent_rate = parent_rate; + } + } + + if (!bestdiv) { + bestdiv = div_mask(width); + *best_parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), 1); + } + + return bestdiv; +} + +static long clk_half_divider_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + struct clk_divider *divider = to_clk_divider(hw); + int div; + + div = clk_half_divider_bestdiv(hw, rate, prate, + divider->width, + divider->flags); + + return DIV_ROUND_UP_ULL(((u64)*prate * 2), div * 2 + 3); +} + +static int clk_half_divider_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_divider *divider = to_clk_divider(hw); + unsigned int value; + unsigned long flags = 0; + u32 val; + + value = DIV_ROUND_UP_ULL(((u64)parent_rate * 2), rate); + value = (value - 3) / 2; + value = min_t(unsigned int, value, div_mask(divider->width)); + + if (divider->lock) + spin_lock_irqsave(divider->lock, flags); + else + __acquire(divider->lock); + + if (divider->flags & CLK_DIVIDER_HIWORD_MASK) { + val = div_mask(divider->width) << (divider->shift + 16); + } else { + val = clk_readl(divider->reg); + val &= ~(div_mask(divider->width) << divider->shift); + } + val |= value << divider->shift; + clk_writel(val, divider->reg); + + if (divider->lock) + spin_unlock_irqrestore(divider->lock, flags); + else + __release(divider->lock); + + return 0; +} + +const struct clk_ops clk_half_divider_ops = { + .recalc_rate = clk_half_divider_recalc_rate, + .round_rate = clk_half_divider_round_rate, + .set_rate = clk_half_divider_set_rate, +}; +EXPORT_SYMBOL_GPL(clk_half_divider_ops); + +/** + * Register a clock branch. + * Most clock branches have a form like + * + * src1 --|--\ + * |M |--[GATE]-[DIV]- + * src2 --|--/ + * + * sometimes without one of those components. + */ +struct clk *rockchip_clk_register_halfdiv(const char *name, + const char *const *parent_names, + u8 num_parents, void __iomem *base, + int muxdiv_offset, u8 mux_shift, + u8 mux_width, u8 mux_flags, + u8 div_shift, u8 div_width, + u8 div_flags, int gate_offset, + u8 gate_shift, u8 gate_flags, + unsigned long flags, + spinlock_t *lock) +{ + struct clk *clk; + struct clk_mux *mux = NULL; + struct clk_gate *gate = NULL; + struct clk_divider *div = NULL; + const struct clk_ops *mux_ops = NULL, *div_ops = NULL, + *gate_ops = NULL; + + if (num_parents > 1) { + mux = kzalloc(sizeof(*mux), GFP_KERNEL); + if (!mux) + return ERR_PTR(-ENOMEM); + + mux->reg = base + muxdiv_offset; + mux->shift = mux_shift; + mux->mask = BIT(mux_width) - 1; + mux->flags = mux_flags; + mux->lock = lock; + mux_ops = (mux_flags & CLK_MUX_READ_ONLY) ? &clk_mux_ro_ops + : &clk_mux_ops; + } + + if (gate_offset >= 0) { + gate = kzalloc(sizeof(*gate), GFP_KERNEL); + if (!gate) + goto err_gate; + + gate->flags = gate_flags; + gate->reg = base + gate_offset; + gate->bit_idx = gate_shift; + gate->lock = lock; + gate_ops = &clk_gate_ops; + } + + if (div_width > 0) { + div = kzalloc(sizeof(*div), GFP_KERNEL); + if (!div) + goto err_div; + + div->flags = div_flags; + div->reg = base + muxdiv_offset; + div->shift = div_shift; + div->width = div_width; + div->lock = lock; + div_ops = &clk_half_divider_ops; + } + + clk = clk_register_composite(NULL, name, parent_names, num_parents, + mux ? &mux->hw : NULL, mux_ops, + div ? &div->hw : NULL, div_ops, + gate ? &gate->hw : NULL, gate_ops, + flags); + + return clk; +err_div: + kfree(gate); +err_gate: + kfree(mux); + return ERR_PTR(-ENOMEM); +} |