[PATCH RFC 10/11] clk: sunxi: rewrite sun6i-ar100 using factors clk

[Chen-Yu Tsai <wens@csie.org>]

sun6i's AR100 clock is a classic factors clk case:

AR100 = ((parent mux) >> p) / (m + 1)

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 drivers/clk/sunxi/clk-sun6i-ar100.c | 235 ++++++++++--------------------------
 1 file changed, 61 insertions(+), 174 deletions(-)

diff --git a/drivers/clk/sunxi/clk-sun6i-ar100.c b/drivers/clk/sunxi/clk-sun6i-ar100.c
index 20887686bdbe..a7f5777834eb 100644
--- a/drivers/clk/sunxi/clk-sun6i-ar100.c
+++ b/drivers/clk/sunxi/clk-sun6i-ar100.c
@@ -8,211 +8,97 @@
  *
  */
 
+#include <linux/bitops.h>
 #include <linux/clk-provider.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/spinlock.h>
 
-#define SUN6I_AR100_MAX_PARENTS		4
-#define SUN6I_AR100_SHIFT_MASK		0x3
-#define SUN6I_AR100_SHIFT_MAX		SUN6I_AR100_SHIFT_MASK
-#define SUN6I_AR100_SHIFT_SHIFT		4
-#define SUN6I_AR100_DIV_MASK		0x1f
-#define SUN6I_AR100_DIV_MAX		(SUN6I_AR100_DIV_MASK + 1)
-#define SUN6I_AR100_DIV_SHIFT		8
-#define SUN6I_AR100_MUX_MASK		0x3
-#define SUN6I_AR100_MUX_SHIFT		16
-
-struct ar100_clk {
-	struct clk_hw hw;
-	void __iomem *reg;
-};
-
-static inline struct ar100_clk *to_ar100_clk(struct clk_hw *hw)
-{
-	return container_of(hw, struct ar100_clk, hw);
-}
-
-static unsigned long ar100_recalc_rate(struct clk_hw *hw,
-				       unsigned long parent_rate)
-{
-	struct ar100_clk *clk = to_ar100_clk(hw);
-	u32 val = readl(clk->reg);
-	int shift = (val >> SUN6I_AR100_SHIFT_SHIFT) & SUN6I_AR100_SHIFT_MASK;
-	int div = (val >> SUN6I_AR100_DIV_SHIFT) & SUN6I_AR100_DIV_MASK;
-
-	return (parent_rate >> shift) / (div + 1);
-}
-
-static int ar100_determine_rate(struct clk_hw *hw,
-				struct clk_rate_request *req)
-{
-	int nparents = clk_hw_get_num_parents(hw);
-	long best_rate = -EINVAL;
-	int i;
-
-	req->best_parent_hw = NULL;
-
-	for (i = 0; i < nparents; i++) {
-		unsigned long parent_rate;
-		unsigned long tmp_rate;
-		struct clk_hw *parent;
-		unsigned long div;
-		int shift;
-
-		parent = clk_hw_get_parent_by_index(hw, i);
-		parent_rate = clk_hw_get_rate(parent);
-		div = DIV_ROUND_UP(parent_rate, req->rate);
-
-		/*
-		 * The AR100 clk contains 2 divisors:
-		 * - one power of 2 divisor
-		 * - one regular divisor
-		 *
-		 * First check if we can safely shift (or divide by a power
-		 * of 2) without losing precision on the requested rate.
-		 */
-		shift = ffs(div) - 1;
-		if (shift > SUN6I_AR100_SHIFT_MAX)
-			shift = SUN6I_AR100_SHIFT_MAX;
-
-		div >>= shift;
-
-		/*
-		 * Then if the divisor is still bigger than what the HW
-		 * actually supports, use a bigger shift (or power of 2
-		 * divider) value and accept to lose some precision.
-		 */
-		while (div > SUN6I_AR100_DIV_MAX) {
-			shift++;
-			div >>= 1;
-			if (shift > SUN6I_AR100_SHIFT_MAX)
-				break;
-		}
-
-		/*
-		 * If the shift value (or power of 2 divider) is bigger
-		 * than what the HW actually support, skip this parent.
-		 */
-		if (shift > SUN6I_AR100_SHIFT_MAX)
-			continue;
-
-		tmp_rate = (parent_rate >> shift) / div;
-		if (!req->best_parent_hw || tmp_rate > best_rate) {
-			req->best_parent_hw = parent;
-			req->best_parent_rate = parent_rate;
-			best_rate = tmp_rate;
-		}
-	}
-
-	if (best_rate < 0)
-		return best_rate;
-
-	req->rate = best_rate;
-
-	return 0;
-}
-
-static int ar100_set_parent(struct clk_hw *hw, u8 index)
-{
-	struct ar100_clk *clk = to_ar100_clk(hw);
-	u32 val = readl(clk->reg);
-
-	if (index >= SUN6I_AR100_MAX_PARENTS)
-		return -EINVAL;
-
-	val &= ~(SUN6I_AR100_MUX_MASK << SUN6I_AR100_MUX_SHIFT);
-	val |= (index << SUN6I_AR100_MUX_SHIFT);
-	writel(val, clk->reg);
-
-	return 0;
-}
+#include "clk-factors.h"
 
-static u8 ar100_get_parent(struct clk_hw *hw)
-{
-	struct ar100_clk *clk = to_ar100_clk(hw);
-	return (readl(clk->reg) >> SUN6I_AR100_MUX_SHIFT) &
-	       SUN6I_AR100_MUX_MASK;
-}
-
-static int ar100_set_rate(struct clk_hw *hw, unsigned long rate,
-			  unsigned long parent_rate)
+/**
+ * sun6i_get_ar100_factors - Calculates factors p, m for AR100
+ *
+ * AR100 rate is calculated as follows
+ * rate = (parent_rate >> p) / (m + 1);
+ */
+static void sun6i_get_ar100_factors(struct factors_request *req)
 {
-	unsigned long div = parent_rate / rate;
-	struct ar100_clk *clk = to_ar100_clk(hw);
-	u32 val = readl(clk->reg);
+	unsigned long div;
 	int shift;
 
-	if (parent_rate % rate)
-		return -EINVAL;
+	/* clock only divides */
+	if (req->rate > req->parent_rate)
+		req->rate = req->parent_rate;
 
-	shift = ffs(div) - 1;
-	if (shift > SUN6I_AR100_SHIFT_MAX)
-		shift = SUN6I_AR100_SHIFT_MAX;
+	div = DIV_ROUND_UP(req->parent_rate, req->rate);
 
-	div >>= shift;
+	if (div < 32)
+		shift = 0;
+	else if (div >> 1 < 32)
+		shift = 1;
+	else if (div >> 2 < 32)
+		shift = 2;
+	else
+		shift = 3;
 
-	if (div > SUN6I_AR100_DIV_MAX)
-		return -EINVAL;
+	div >>= shift;
 
-	val &= ~((SUN6I_AR100_SHIFT_MASK << SUN6I_AR100_SHIFT_SHIFT) |
-		 (SUN6I_AR100_DIV_MASK << SUN6I_AR100_DIV_SHIFT));
-	val |= (shift << SUN6I_AR100_SHIFT_SHIFT) |
-	       (div << SUN6I_AR100_DIV_SHIFT);
-	writel(val, clk->reg);
+	if (div > 32)
+		div = 32;
 
-	return 0;
+	req->rate = (req->parent_rate >> shift) / div;
+	req->m = div - 1;
+	req->p = shift;
 }
 
-static struct clk_ops ar100_ops = {
-	.recalc_rate = ar100_recalc_rate,
-	.determine_rate = ar100_determine_rate,
-	.set_parent = ar100_set_parent,
-	.get_parent = ar100_get_parent,
-	.set_rate = ar100_set_rate,
+static const struct clk_factors_config sun6i_ar100_config = {
+	.mwidth = 5,
+	.mshift = 8,
+	.pwidth = 2,
+	.pshift = 4,
 };
 
+static const struct factors_data sun6i_ar100_data __initconst = {
+	.mux = 16,
+	.muxmask = GENMASK(1, 0),
+	.table = &sun6i_ar100_config,
+	.getter = sun6i_get_ar100_factors,
+};
+
+static DEFINE_SPINLOCK(sun6i_ar100_lock);
+
 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
 {
-	const char *parents[SUN6I_AR100_MAX_PARENTS];
 	struct device_node *np = pdev->dev.of_node;
-	const char *clk_name = np->name;
-	struct clk_init_data init;
-	struct ar100_clk *ar100;
 	struct resource *r;
+	void __iomem *reg;
 	struct clk *clk;
-	int nparents;
-
-	ar100 = devm_kzalloc(&pdev->dev, sizeof(*ar100), GFP_KERNEL);
-	if (!ar100)
-		return -ENOMEM;
 
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	ar100->reg = devm_ioremap_resource(&pdev->dev, r);
-	if (IS_ERR(ar100->reg))
-		return PTR_ERR(ar100->reg);
+	reg = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(reg))
+		return PTR_ERR(reg);
 
-	nparents = of_clk_get_parent_count(np);
-	if (nparents > SUN6I_AR100_MAX_PARENTS)
-		nparents = SUN6I_AR100_MAX_PARENTS;
-
-	of_clk_parent_fill(np, parents, nparents);
+	clk = sunxi_factors_register(np, &sun6i_ar100_data, &sun6i_ar100_lock,
+				     reg);
+	if (!clk)
+		return -ENOMEM;
 
-	of_property_read_string(np, "clock-output-names", &clk_name);
+	platform_set_drvdata(pdev, clk);
 
-	init.name = clk_name;
-	init.ops = &ar100_ops;
-	init.parent_names = parents;
-	init.num_parents = nparents;
-	init.flags = 0;
+	return 0;
+}
 
-	ar100->hw.init = &init;
+static int sun6i_a31_ar100_clk_remove(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct clk *clk = platform_get_drvdata(pdev);
 
-	clk = clk_register(&pdev->dev, &ar100->hw);
-	if (IS_ERR(clk))
-		return PTR_ERR(clk);
+	sunxi_factors_unregister(np, clk);
 
-	return of_clk_add_provider(np, of_clk_src_simple_get, clk);
+	return 0;
 }
 
 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
@@ -227,6 +113,7 @@ static struct platform_driver sun6i_a31_ar100_clk_driver = {
 		.of_match_table = sun6i_a31_ar100_clk_dt_ids,
 	},
 	.probe = sun6i_a31_ar100_clk_probe,
+	.remove = sun6i_a31_ar100_clk_remove,
 };
 module_platform_driver(sun6i_a31_ar100_clk_driver);
 
-- 
2.7.0