diff options
Diffstat (limited to 'drivers/clk/tegra/clk-divider.c')
| -rw-r--r-- | drivers/clk/tegra/clk-divider.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/drivers/clk/tegra/clk-divider.c b/drivers/clk/tegra/clk-divider.c new file mode 100644 index 00000000000..4d75b1f37e3 --- /dev/null +++ b/drivers/clk/tegra/clk-divider.c @@ -0,0 +1,187 @@ +/* + * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/kernel.h> +#include <linux/io.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/clk-provider.h> +#include <linux/clk.h> + +#include "clk.h" + +#define pll_out_override(p) (BIT((p->shift - 6))) +#define div_mask(d) ((1 << (d->width)) - 1) +#define get_mul(d) (1 << d->frac_width) +#define get_max_div(d) div_mask(d) + +#define PERIPH_CLK_UART_DIV_ENB BIT(24) + +static int get_div(struct tegra_clk_frac_div *divider, unsigned long rate, + unsigned long parent_rate) +{ + s64 divider_ux1 = parent_rate; + u8 flags = divider->flags; + int mul; + + if (!rate) + return 0; + + mul = get_mul(divider); + + if (!(flags & TEGRA_DIVIDER_INT)) + divider_ux1 *= mul; + + if (flags & TEGRA_DIVIDER_ROUND_UP) + divider_ux1 += rate - 1; + + do_div(divider_ux1, rate); + + if (flags & TEGRA_DIVIDER_INT) + divider_ux1 *= mul; + + divider_ux1 -= mul; + + if (divider_ux1 < 0) + return 0; + + if (divider_ux1 > get_max_div(divider)) + return -EINVAL; + + return divider_ux1; +} + +static unsigned long clk_frac_div_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct tegra_clk_frac_div *divider = to_clk_frac_div(hw); + u32 reg; + int div, mul; + u64 rate = parent_rate; + + reg = readl_relaxed(divider->reg) >> divider->shift; + div = reg & div_mask(divider); + + mul = get_mul(divider); + div += mul; + + rate *= mul; + rate += div - 1; + do_div(rate, div); + + return rate; +} + +static long clk_frac_div_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + struct tegra_clk_frac_div *divider = to_clk_frac_div(hw); + int div, mul; + unsigned long output_rate = *prate; + + if (!rate) + return output_rate; + + div = get_div(divider, rate, output_rate); + if (div < 0) + return *prate; + + mul = get_mul(divider); + + return DIV_ROUND_UP(output_rate * mul, div + mul); +} + +static int clk_frac_div_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct tegra_clk_frac_div *divider = to_clk_frac_div(hw); + int div; + unsigned long flags = 0; + u32 val; + + div = get_div(divider, rate, parent_rate); + if (div < 0) + return div; + + if (divider->lock) + spin_lock_irqsave(divider->lock, flags); + + val = readl_relaxed(divider->reg); + val &= ~(div_mask(divider) << divider->shift); + val |= div << divider->shift; + + if (divider->flags & TEGRA_DIVIDER_UART) { + if (div) + val |= PERIPH_CLK_UART_DIV_ENB; + else + val &= ~PERIPH_CLK_UART_DIV_ENB; + } + + if (divider->flags & TEGRA_DIVIDER_FIXED) + val |= pll_out_override(divider); + + writel_relaxed(val, divider->reg); + + if (divider->lock) + spin_unlock_irqrestore(divider->lock, flags); + + return 0; +} + +const struct clk_ops tegra_clk_frac_div_ops = { + .recalc_rate = clk_frac_div_recalc_rate, + .set_rate = clk_frac_div_set_rate, + .round_rate = clk_frac_div_round_rate, +}; + +struct clk *tegra_clk_register_divider(const char *name, + const char *parent_name, void __iomem *reg, + unsigned long flags, u8 clk_divider_flags, u8 shift, u8 width, + u8 frac_width, spinlock_t *lock) +{ + struct tegra_clk_frac_div *divider; + struct clk *clk; + struct clk_init_data init; + + divider = kzalloc(sizeof(*divider), GFP_KERNEL); + if (!divider) { + pr_err("%s: could not allocate fractional divider clk\n", + __func__); + return ERR_PTR(-ENOMEM); + } + + init.name = name; + init.ops = &tegra_clk_frac_div_ops; + init.flags = flags; + init.parent_names = parent_name ? &parent_name : NULL; + init.num_parents = parent_name ? 1 : 0; + + divider->reg = reg; + divider->shift = shift; + divider->width = width; + divider->frac_width = frac_width; + divider->lock = lock; + divider->flags = clk_divider_flags; + + /* Data in .init is copied by clk_register(), so stack variable OK */ + divider->hw.init = &init; + + clk = clk_register(NULL, ÷r->hw); + if (IS_ERR(clk)) + kfree(divider); + + return clk; +} |