drivers/clk/zynq/pll.c

   1 /*
   2  * Zynq PLL driver
   3  *
   4  *  Copyright (C) 2013 Xilinx
   5  *
   6  *  Sören Brinkmann <soren.brinkmann@xilinx.com>
   7  *
   8  * This program is free software: you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License v2 as published by
  10  * the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  *
  20  */
  21 #include <linux/clk/zynq.h>
  22 #include <linux/clk-provider.h>
  23 #include <linux/slab.h>
  24 #include <linux/io.h>
  25
  26 /**
  27  * struct zynq_pll
  28  * @hw:         Handle between common and hardware-specific interfaces
  29  * @pll_ctrl:   PLL control register
  30  * @pll_status: PLL status register
  31  * @lock:       Register lock
  32  * @lockbit:    Indicates the associated PLL_LOCKED bit in the PLL status
  33  *              register.
  34  */
  35 struct zynq_pll {
  36         struct clk_hw   hw;
  37         void __iomem    *pll_ctrl;
  38         void __iomem    *pll_status;
  39         spinlock_t      *lock;
  40         u8              lockbit;
  41 };
  42 #define to_zynq_pll(_hw)        container_of(_hw, struct zynq_pll, hw)
  43
  44 /* Register bitfield defines */
  45 #define PLLCTRL_FBDIV_MASK      0x7f000
  46 #define PLLCTRL_FBDIV_SHIFT     12
  47 #define PLLCTRL_BPQUAL_MASK     (1 << 3)
  48 #define PLLCTRL_PWRDWN_MASK     2
  49 #define PLLCTRL_PWRDWN_SHIFT    1
  50 #define PLLCTRL_RESET_MASK      1
  51 #define PLLCTRL_RESET_SHIFT     0
  52
  53 #define PLL_FBDIV_MIN   13
  54 #define PLL_FBDIV_MAX   66
  55
  56 /**
  57  * zynq_pll_round_rate() - Round a clock frequency
  58  * @hw:         Handle between common and hardware-specific interfaces
  59  * @rate:       Desired clock frequency
  60  * @prate:      Clock frequency of parent clock
  61  * Returns frequency closest to @rate the hardware can generate.
  62  */
  63 static long zynq_pll_round_rate(struct clk_hw *hw, unsigned long rate,
  64                 unsigned long *prate)
  65 {
  66         u32 fbdiv;
  67
  68         fbdiv = DIV_ROUND_CLOSEST(rate, *prate);
  69         if (fbdiv < PLL_FBDIV_MIN)
  70                 fbdiv = PLL_FBDIV_MIN;
  71         else if (fbdiv > PLL_FBDIV_MAX)
  72                 fbdiv = PLL_FBDIV_MAX;
  73
  74         return *prate * fbdiv;
  75 }
  76
  77 /**
  78  * zynq_pll_recalc_rate() - Recalculate clock frequency
  79  * @hw:                 Handle between common and hardware-specific interfaces
  80  * @parent_rate:        Clock frequency of parent clock
  81  * Returns current clock frequency.
  82  */
  83 static unsigned long zynq_pll_recalc_rate(struct clk_hw *hw,
  84                 unsigned long parent_rate)
  85 {
  86         struct zynq_pll *clk = to_zynq_pll(hw);
  87         u32 fbdiv;
  88
  89         /*
  90          * makes probably sense to redundantly save fbdiv in the struct
  91          * zynq_pll to save the IO access.
  92          */
  93         fbdiv = (clk_readl(clk->pll_ctrl) & PLLCTRL_FBDIV_MASK) >>
  94                         PLLCTRL_FBDIV_SHIFT;
  95
  96         return parent_rate * fbdiv;
  97 }
  98
  99 /**
 100  * zynq_pll_is_enabled - Check if a clock is enabled
 101  * @hw:         Handle between common and hardware-specific interfaces
 102  * Returns 1 if the clock is enabled, 0 otherwise.
 103  *
 104  * Not sure this is a good idea, but since disabled means bypassed for
 105  * this clock implementation we say we are always enabled.
 106  */
 107 static int zynq_pll_is_enabled(struct clk_hw *hw)
 108 {
 109         unsigned long flags = 0;
 110         u32 reg;
 111         struct zynq_pll *clk = to_zynq_pll(hw);
 112
 113         spin_lock_irqsave(clk->lock, flags);
 114
 115         reg = clk_readl(clk->pll_ctrl);
 116
 117         spin_unlock_irqrestore(clk->lock, flags);
 118
 119         return !(reg & (PLLCTRL_RESET_MASK | PLLCTRL_PWRDWN_MASK));
 120 }
 121
 122 /**
 123  * zynq_pll_enable - Enable clock
 124  * @hw:         Handle between common and hardware-specific interfaces
 125  * Returns 0 on success
 126  */
 127 static int zynq_pll_enable(struct clk_hw *hw)
 128 {
 129         unsigned long flags = 0;
 130         u32 reg;
 131         struct zynq_pll *clk = to_zynq_pll(hw);
 132
 133         if (zynq_pll_is_enabled(hw))
 134                 return 0;
 135
 136         pr_info("PLL: enable\n");
 137
 138         /* Power up PLL and wait for lock */
 139         spin_lock_irqsave(clk->lock, flags);
 140
 141         reg = clk_readl(clk->pll_ctrl);
 142         reg &= ~(PLLCTRL_RESET_MASK | PLLCTRL_PWRDWN_MASK);
 143         clk_writel(reg, clk->pll_ctrl);
 144         while (!(clk_readl(clk->pll_status) & (1 << clk->lockbit)))
 145                 ;
 146
 147         spin_unlock_irqrestore(clk->lock, flags);
 148
 149         return 0;
 150 }
 151
 152 /**
 153  * zynq_pll_disable - Disable clock
 154  * @hw:         Handle between common and hardware-specific interfaces
 155  * Returns 0 on success
 156  */
 157 static void zynq_pll_disable(struct clk_hw *hw)
 158 {
 159         unsigned long flags = 0;
 160         u32 reg;
 161         struct zynq_pll *clk = to_zynq_pll(hw);
 162
 163         if (!zynq_pll_is_enabled(hw))
 164                 return;
 165
 166         pr_info("PLL: shutdown\n");
 167
 168         /* shut down PLL */
 169         spin_lock_irqsave(clk->lock, flags);
 170
 171         reg = clk_readl(clk->pll_ctrl);
 172         reg |= PLLCTRL_RESET_MASK | PLLCTRL_PWRDWN_MASK;
 173         clk_writel(reg, clk->pll_ctrl);
 174
 175         spin_unlock_irqrestore(clk->lock, flags);
 176 }
 177
 178 static const struct clk_ops zynq_pll_ops = {
 179         .enable = zynq_pll_enable,
 180         .disable = zynq_pll_disable,
 181         .is_enabled = zynq_pll_is_enabled,
 182         .round_rate = zynq_pll_round_rate,
 183         .recalc_rate = zynq_pll_recalc_rate
 184 };
 185
 186 /**
 187  * clk_register_zynq_pll() - Register PLL with the clock framework
 188  * @name        PLL name
 189  * @parent      Parent clock name
 190  * @pll_ctrl    Pointer to PLL control register
 191  * @pll_status  Pointer to PLL status register
 192  * @lock_index  Bit index to this PLL's lock status bit in @pll_status
 193  * @lock        Register lock
 194  * Returns handle to the registered clock.
 195  */
 196 struct clk *clk_register_zynq_pll(const char *name, const char *parent,
 197                 void __iomem *pll_ctrl, void __iomem *pll_status, u8 lock_index,
 198                 spinlock_t *lock)
 199 {
 200         struct zynq_pll *pll;
 201         struct clk *clk;
 202         u32 reg;
 203         const char *parent_arr[1] = {parent};
 204         unsigned long flags = 0;
 205         struct clk_init_data initd = {
 206                 .name = name,
 207                 .parent_names = parent_arr,
 208                 .ops = &zynq_pll_ops,
 209                 .num_parents = 1,
 210                 .flags = 0
 211         };
 212
 213         pll = kmalloc(sizeof(*pll), GFP_KERNEL);
 214         if (!pll) {
 215                 pr_err("%s: Could not allocate Zynq PLL clk.\n", __func__);
 216                 return ERR_PTR(-ENOMEM);
 217         }
 218
 219         /* Populate the struct */
 220         pll->hw.init = &initd;
 221         pll->pll_ctrl = pll_ctrl;
 222         pll->pll_status = pll_status;
 223         pll->lockbit = lock_index;
 224         pll->lock = lock;
 225
 226         spin_lock_irqsave(pll->lock, flags);
 227
 228         reg = clk_readl(pll->pll_ctrl);
 229         reg &= ~PLLCTRL_BPQUAL_MASK;
 230         clk_writel(reg, pll->pll_ctrl);
 231
 232         spin_unlock_irqrestore(pll->lock, flags);
 233
 234         clk = clk_register(NULL, &pll->hw);
 235         if (WARN_ON(IS_ERR(clk)))
 236                 goto free_pll;
 237
 238         return clk;
 239
 240 free_pll:
 241         kfree(pll);
 242
 243         return clk;
 244 }