Patchwork [v2,2/5] clk: zynq: Factor out PLL driver

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Submitter Soren Brinkmann
Date May 13, 2013, 5:46 p.m.
Message ID <1368467199-8702-3-git-send-email-soren.brinkmann@xilinx.com>
Download mbox | patch
Permalink /patch/243472/
State New
Headers show

Comments

Soren Brinkmann - May 13, 2013, 5:46 p.m.
Refactor the PLL driver so it works with the clock controller driver.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/clk/zynq/pll.c | 235 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 235 insertions(+)
 create mode 100644 drivers/clk/zynq/pll.c

Patch

diff --git a/drivers/clk/zynq/pll.c b/drivers/clk/zynq/pll.c
new file mode 100644
index 0000000..47e307c
--- /dev/null
+++ b/drivers/clk/zynq/pll.c
@@ -0,0 +1,235 @@ 
+/*
+ * Zynq PLL driver
+ *
+ *  Copyright (C) 2013 Xilinx
+ *
+ *  Sören Brinkmann <soren.brinkmann@xilinx.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that 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/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
+
+/**
+ * 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 < 13)
+		fbdiv = 13;
+	else if (fbdiv > 66)
+		fbdiv = 66;
+
+	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
+ * @np	Pointer to the DT device node
+ */
+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) {
+		pr_err("%s: Could not allocate Zynq PLL clk.\n", __func__);
+		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;
+}