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// 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;
}
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