diff options
Diffstat (limited to 'drivers/clk/zynq/pll.c')
| -rw-r--r-- | drivers/clk/zynq/pll.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/drivers/clk/zynq/pll.c b/drivers/clk/zynq/pll.c new file mode 100644 index 000000000..dcb2037a9 --- /dev/null +++ b/drivers/clk/zynq/pll.c @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Zynq PLL driver + * + * Copyright (C) 2013 Xilinx + * + * Sören Brinkmann <soren.brinkmann@xilinx.com> + */ +#include <linux/clk/zynq.h> +#include <linux/clk-provider.h> +#include <linux/slab.h> +#include <linux/io.h> + +/** + * struct zynq_pll + * @hw: Handle between common and hardware-specific interfaces + * @pll_ctrl: PLL control register + * @pll_status: PLL status register + * @lock: Register lock + * @lockbit: Indicates the associated PLL_LOCKED bit in the PLL status + * register. + */ +struct zynq_pll { + struct clk_hw hw; + void __iomem *pll_ctrl; + void __iomem *pll_status; + spinlock_t *lock; + u8 lockbit; +}; +#define to_zynq_pll(_hw) container_of(_hw, struct zynq_pll, hw) + +/* Register bitfield defines */ +#define PLLCTRL_FBDIV_MASK 0x7f000 +#define PLLCTRL_FBDIV_SHIFT 12 +#define PLLCTRL_BPQUAL_MASK (1 << 3) +#define PLLCTRL_PWRDWN_MASK 2 +#define PLLCTRL_PWRDWN_SHIFT 1 +#define PLLCTRL_RESET_MASK 1 +#define PLLCTRL_RESET_SHIFT 0 + +#define PLL_FBDIV_MIN 13 +#define PLL_FBDIV_MAX 66 + +/** + * zynq_pll_round_rate() - Round a clock frequency + * @hw: Handle between common and hardware-specific interfaces + * @rate: Desired clock frequency + * @prate: Clock frequency of parent clock + * Returns frequency closest to @rate the hardware can generate. + */ +static long zynq_pll_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + u32 fbdiv; + + fbdiv = DIV_ROUND_CLOSEST(rate, *prate); + if (fbdiv < PLL_FBDIV_MIN) + fbdiv = PLL_FBDIV_MIN; + else if (fbdiv > PLL_FBDIV_MAX) + fbdiv = PLL_FBDIV_MAX; + + return *prate * fbdiv; +} + +/** + * zynq_pll_recalc_rate() - Recalculate clock frequency + * @hw: Handle between common and hardware-specific interfaces + * @parent_rate: Clock frequency of parent clock + * Returns current clock frequency. + */ +static unsigned long zynq_pll_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct zynq_pll *clk = to_zynq_pll(hw); + u32 fbdiv; + + /* + * makes probably sense to redundantly save fbdiv in the struct + * zynq_pll to save the IO access. + */ + fbdiv = (readl(clk->pll_ctrl) & PLLCTRL_FBDIV_MASK) >> + PLLCTRL_FBDIV_SHIFT; + + return parent_rate * fbdiv; +} + +/** + * zynq_pll_is_enabled - Check if a clock is enabled + * @hw: Handle between common and hardware-specific interfaces + * Returns 1 if the clock is enabled, 0 otherwise. + * + * Not sure this is a good idea, but since disabled means bypassed for + * this clock implementation we say we are always enabled. + */ +static int zynq_pll_is_enabled(struct clk_hw *hw) +{ + unsigned long flags = 0; + u32 reg; + struct zynq_pll *clk = to_zynq_pll(hw); + + spin_lock_irqsave(clk->lock, flags); + + reg = readl(clk->pll_ctrl); + + spin_unlock_irqrestore(clk->lock, flags); + + return !(reg & (PLLCTRL_RESET_MASK | PLLCTRL_PWRDWN_MASK)); +} + +/** + * zynq_pll_enable - Enable clock + * @hw: Handle between common and hardware-specific interfaces + * Returns 0 on success + */ +static int zynq_pll_enable(struct clk_hw *hw) +{ + unsigned long flags = 0; + u32 reg; + struct zynq_pll *clk = to_zynq_pll(hw); + + if (zynq_pll_is_enabled(hw)) + return 0; + + pr_info("PLL: enable\n"); + + /* Power up PLL and wait for lock */ + spin_lock_irqsave(clk->lock, flags); + + reg = readl(clk->pll_ctrl); + reg &= ~(PLLCTRL_RESET_MASK | PLLCTRL_PWRDWN_MASK); + writel(reg, clk->pll_ctrl); + while (!(readl(clk->pll_status) & (1 << clk->lockbit))) + ; + + spin_unlock_irqrestore(clk->lock, flags); + + return 0; +} + +/** + * zynq_pll_disable - Disable clock + * @hw: Handle between common and hardware-specific interfaces + * Returns 0 on success + */ +static void zynq_pll_disable(struct clk_hw *hw) +{ + unsigned long flags = 0; + u32 reg; + struct zynq_pll *clk = to_zynq_pll(hw); + + if (!zynq_pll_is_enabled(hw)) + return; + + pr_info("PLL: shutdown\n"); + + /* shut down PLL */ + spin_lock_irqsave(clk->lock, flags); + + reg = readl(clk->pll_ctrl); + reg |= PLLCTRL_RESET_MASK | PLLCTRL_PWRDWN_MASK; + writel(reg, clk->pll_ctrl); + + spin_unlock_irqrestore(clk->lock, flags); +} + +static const struct clk_ops zynq_pll_ops = { + .enable = zynq_pll_enable, + .disable = zynq_pll_disable, + .is_enabled = zynq_pll_is_enabled, + .round_rate = zynq_pll_round_rate, + .recalc_rate = zynq_pll_recalc_rate +}; + +/** + * clk_register_zynq_pll() - Register PLL with the clock framework + * @name PLL name + * @parent Parent clock name + * @pll_ctrl Pointer to PLL control register + * @pll_status Pointer to PLL status register + * @lock_index Bit index to this PLL's lock status bit in @pll_status + * @lock Register lock + * Returns handle to the registered clock. + */ +struct clk *clk_register_zynq_pll(const char *name, const char *parent, + void __iomem *pll_ctrl, void __iomem *pll_status, u8 lock_index, + spinlock_t *lock) +{ + struct zynq_pll *pll; + struct clk *clk; + u32 reg; + const char *parent_arr[1] = {parent}; + unsigned long flags = 0; + struct clk_init_data initd = { + .name = name, + .parent_names = parent_arr, + .ops = &zynq_pll_ops, + .num_parents = 1, + .flags = 0 + }; + + pll = kmalloc(sizeof(*pll), GFP_KERNEL); + if (!pll) + return ERR_PTR(-ENOMEM); + + /* Populate the struct */ + pll->hw.init = &initd; + pll->pll_ctrl = pll_ctrl; + pll->pll_status = pll_status; + pll->lockbit = lock_index; + pll->lock = lock; + + spin_lock_irqsave(pll->lock, flags); + + reg = readl(pll->pll_ctrl); + reg &= ~PLLCTRL_BPQUAL_MASK; + writel(reg, pll->pll_ctrl); + + spin_unlock_irqrestore(pll->lock, flags); + + clk = clk_register(NULL, &pll->hw); + if (WARN_ON(IS_ERR(clk))) + goto free_pll; + + return clk; + +free_pll: + kfree(pll); + + return clk; +} |