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From:   Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
To:     linux-clk@vger.kernel.org
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        devel@driverdev.osuosl.org, sboyd@kernel.org, robh+dt@kernel.org,
        gregkh@linuxfoundation.org, mturquette@baylibre.com,
        Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Subject: [PATCH v6 5/8] clk: clock-wizard: Add support for fractional support
Date:   Fri, 28 Aug 2020 19:09:53 +0530
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Currently the set rate granularity is to integral divisors.
Add support for the fractional divisors.
Only the first output0 is fractional in the hardware.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
---
v6:
remove unnecessary typecast
remove unnecessary locks
use polled timeout

 drivers/clk/clk-xlnx-clock-wizard.c | 166 +++++++++++++++++++++++++++++++++---
 1 file changed, 153 insertions(+), 13 deletions(-)

diff --git a/drivers/clk/clk-xlnx-clock-wizard.c b/drivers/clk/clk-xlnx-clock-wizard.c
index 8dfcec8..1af59a4 100644
--- a/drivers/clk/clk-xlnx-clock-wizard.c
+++ b/drivers/clk/clk-xlnx-clock-wizard.c
@@ -29,20 +29,25 @@
 
 #define WZRD_CLKFBOUT_MULT_SHIFT	8
 #define WZRD_CLKFBOUT_MULT_MASK		(0xff << WZRD_CLKFBOUT_MULT_SHIFT)
+#define WZRD_CLKFBOUT_FRAC_SHIFT	16
+#define WZRD_CLKFBOUT_FRAC_MASK		(0x3ff << WZRD_CLKFBOUT_FRAC_SHIFT)
 #define WZRD_DIVCLK_DIVIDE_SHIFT	0
 #define WZRD_DIVCLK_DIVIDE_MASK		(0xff << WZRD_DIVCLK_DIVIDE_SHIFT)
 #define WZRD_CLKOUT_DIVIDE_SHIFT	0
 #define WZRD_CLKOUT_DIVIDE_WIDTH	8
 #define WZRD_CLKOUT_DIVIDE_MASK		(0xff << WZRD_DIVCLK_DIVIDE_SHIFT)
+#define WZRD_CLKOUT_FRAC_SHIFT		8
+#define WZRD_CLKOUT_FRAC_MASK		0x3ff
 
 #define WZRD_DR_MAX_INT_DIV_VALUE	255
-#define WZRD_DR_NUM_RETRIES		10000
 #define WZRD_DR_STATUS_REG_OFFSET	0x04
 #define WZRD_DR_LOCK_BIT_MASK		0x00000001
 #define WZRD_DR_INIT_REG_OFFSET		0x25C
 #define WZRD_DR_DIV_TO_PHASE_OFFSET	4
 #define WZRD_DR_BEGIN_DYNA_RECONF	0x03
 
+#define WZRD_USEC_POLL		10
+#define WZRD_TIMEOUT_POLL		1000
 /* Get the mask from width */
 #define div_mask(width)			((1 << (width)) - 1)
 
@@ -52,6 +57,7 @@
 enum clk_wzrd_int_clks {
 	wzrd_clk_mul,
 	wzrd_clk_mul_div,
+	wzrd_clk_mul_frac,
 	wzrd_clk_int_max
 };
 
@@ -185,6 +191,134 @@ static const struct clk_ops clk_wzrd_clk_divider_ops = {
 	.recalc_rate = clk_wzrd_recalc_rate,
 };
 
+static unsigned long clk_wzrd_recalc_ratef(struct clk_hw *hw,
+					   unsigned long parent_rate)
+{
+	unsigned int val;
+	u32 div, frac;
+	struct clk_wzrd_divider *divider = to_clk_wzrd_divider(hw);
+	void __iomem *div_addr = divider->base + divider->offset;
+
+	val = readl(div_addr);
+	div = val & div_mask(divider->width);
+	frac = (val >> WZRD_CLKOUT_FRAC_SHIFT) & WZRD_CLKOUT_FRAC_MASK;
+
+	return ((parent_rate * 1000) / ((div * 1000) + frac));
+}
+
+static int clk_wzrd_dynamic_reconfig_f(struct clk_hw *hw, unsigned long rate,
+				       unsigned long parent_rate)
+{
+	int err;
+	u32 value, pre;
+	unsigned long rate_div, f, clockout0_div;
+	struct clk_wzrd_divider *divider = to_clk_wzrd_divider(hw);
+	void __iomem *div_addr = divider->base + divider->offset;
+
+	rate_div = ((parent_rate * 1000) / rate);
+	clockout0_div = rate_div / 1000;
+
+	pre = DIV_ROUND_CLOSEST((parent_rate * 1000), rate);
+	f = (u32)(pre - (clockout0_div * 1000));
+	f = f & WZRD_CLKOUT_FRAC_MASK;
+
+	value = ((f << WZRD_CLKOUT_DIVIDE_WIDTH) | (clockout0_div &
+			WZRD_CLKOUT_DIVIDE_MASK));
+
+	/* Set divisor and clear phase offset */
+	writel(value, div_addr);
+	writel(0x0, div_addr + WZRD_DR_DIV_TO_PHASE_OFFSET);
+
+	/* Check status register */
+	err= readl_poll_timeout(divider->base + WZRD_DR_STATUS_REG_OFFSET, value,
+				value & WZRD_DR_LOCK_BIT_MASK,
+				WZRD_USEC_POLL, WZRD_TIMEOUT_POLL);
+	if (err)
+		return err;
+
+	/* Initiate reconfiguration */
+	writel(WZRD_DR_BEGIN_DYNA_RECONF,
+	       divider->base + WZRD_DR_INIT_REG_OFFSET);
+
+	/* Check status register */
+	err= readl_poll_timeout(divider->base + WZRD_DR_STATUS_REG_OFFSET, value,
+				value & WZRD_DR_LOCK_BIT_MASK,
+				WZRD_USEC_POLL, WZRD_TIMEOUT_POLL);
+
+	return err;
+}
+
+static long clk_wzrd_round_rate_f(struct clk_hw *hw, unsigned long rate,
+				  unsigned long *prate)
+{
+	return rate;
+}
+
+static const struct clk_ops clk_wzrd_clk_divider_ops_f = {
+	.round_rate = clk_wzrd_round_rate_f,
+	.set_rate = clk_wzrd_dynamic_reconfig_f,
+	.recalc_rate = clk_wzrd_recalc_ratef,
+};
+
+static struct clk *clk_wzrd_register_divf(struct device *dev,
+					  const char *name,
+					  const char *parent_name,
+					  unsigned long flags,
+					  void __iomem *base, u16 offset,
+					  u8 shift, u8 width,
+					  u8 clk_divider_flags,
+					  const struct clk_div_table *table,
+					  spinlock_t *lock)
+{
+	struct clk_wzrd_divider *div;
+	struct clk_hw *hw;
+	struct clk_init_data init;
+	int ret;
+
+	if (clk_divider_flags & CLK_DIVIDER_HIWORD_MASK) {
+		if (width + shift > 16) {
+			pr_warn("divider value exceeds LOWORD field\n");
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	/* allocate the divider */
+	div = kzalloc(sizeof(*div), GFP_KERNEL);
+	if (!div)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+
+	if (clk_divider_flags & CLK_DIVIDER_READ_ONLY)
+		init.ops = &clk_divider_ro_ops;
+	else
+		init.ops = &clk_wzrd_clk_divider_ops_f;
+
+	init.flags = flags;
+	init.parent_names = (parent_name ? &parent_name : NULL);
+	init.num_parents = (parent_name ? 1 : 0);
+
+	/* struct clk_divider assignments */
+	div->base = base;
+	div->offset = offset;
+	div->shift = shift;
+	div->width = width;
+	div->flags = clk_divider_flags;
+	div->lock = lock;
+	div->hw.init = &init;
+	div->table = table;
+
+	/* register the clock */
+	hw = &div->hw;
+	ret = clk_hw_register(dev, hw);
+	if (ret) {
+		kfree(div);
+		return ERR_PTR(ret);
+	}
+
+	return hw->clk;
+}
+
 static struct clk *clk_wzrd_register_divider(struct device *dev,
 					     const char *name,
 					     const char *parent_name,
@@ -303,7 +437,7 @@ static SIMPLE_DEV_PM_OPS(clk_wzrd_dev_pm_ops, clk_wzrd_suspend,
 static int clk_wzrd_probe(struct platform_device *pdev)
 {
 	int i, ret;
-	u32 reg;
+	u32 reg, reg_f, mult;
 	unsigned long rate;
 	const char *clk_name;
 	struct clk_wzrd *clk_wzrd;
@@ -355,17 +489,13 @@ static int clk_wzrd_probe(struct platform_device *pdev)
 		goto err_disable_clk;
 	}
 
-	/* we don't support fractional div/mul yet */
-	reg = readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
-		    WZRD_CLKFBOUT_FRAC_EN;
-	reg |= readl(clk_wzrd->base + WZRD_CLK_CFG_REG(2)) &
-		     WZRD_CLKOUT0_FRAC_EN;
-	if (reg)
-		dev_warn(&pdev->dev, "fractional div/mul not supported\n");
-
 	/* register multiplier */
 	reg = (readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
 		     WZRD_CLKFBOUT_MULT_MASK) >> WZRD_CLKFBOUT_MULT_SHIFT;
+	reg_f = (readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
+		     WZRD_CLKFBOUT_FRAC_MASK) >> WZRD_CLKFBOUT_FRAC_SHIFT;
+
+	mult = ((reg * 1000) + reg_f);
 	clk_name = kasprintf(GFP_KERNEL, "%s_mul", dev_name(&pdev->dev));
 	if (!clk_name) {
 		ret = -ENOMEM;
@@ -374,7 +504,7 @@ static int clk_wzrd_probe(struct platform_device *pdev)
 	clk_wzrd->clks_internal[wzrd_clk_mul] = clk_register_fixed_factor
 			(&pdev->dev, clk_name,
 			 __clk_get_name(clk_wzrd->clk_in1),
-			 0, reg, 1);
+			0, mult, 1000);
 	kfree(clk_name);
 	if (IS_ERR(clk_wzrd->clks_internal[wzrd_clk_mul])) {
 		dev_err(&pdev->dev, "unable to register fixed-factor clock\n");
@@ -413,8 +543,18 @@ static int clk_wzrd_probe(struct platform_device *pdev)
 			ret = -EINVAL;
 			goto err_rm_int_clks;
 		}
-		clk_wzrd->clkout[i] = clk_wzrd_register_divider(&pdev->dev,
-								clkout_name,
+		if (!i)
+			clk_wzrd->clkout[i] = clk_wzrd_register_divf
+				(&pdev->dev, clkout_name,
+				clk_name, 0,
+				clk_wzrd->base, (WZRD_CLK_CFG_REG(2) + i * 12),
+				WZRD_CLKOUT_DIVIDE_SHIFT,
+				WZRD_CLKOUT_DIVIDE_WIDTH,
+				CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ALLOW_ZERO,
+				NULL, &clkwzrd_lock);
+		else
+			clk_wzrd->clkout[i] = clk_wzrd_register_divider
+				(&pdev->dev, clkout_name,
 				clk_name, 0,
 				clk_wzrd->base, (WZRD_CLK_CFG_REG(2) + i * 12),
 				WZRD_CLKOUT_DIVIDE_SHIFT,
-- 
2.1.1