drm/sun4i: Add support for H3 HDMI PHY variant

While A83T HDMI PHY seems to be just customized Synopsys HDMI PHY, H3
HDMI PHY is completely custom PHY.

However, they still have many things in common like clock and reset
setup, setting sync polarity and more.

Add support for H3 HDMI PHY variant.

While documentation exists for this PHY variant, it doesn't go in great
details. Because of that, almost all settings are copied from BSP linux
4.4. Interestingly, those settings are slightly different to those found
in a older BSP with Linux 3.4. For now, no user visible difference was
found between them.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180301213442.16677-13-jernej.skrabec@siol.net

1 files changed, 132 insertions, 0 deletions

diff --git a/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c b/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
new file mode 100644
index 0000000..faea449
--- /dev/null
+++ b/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Jernej Skrabec <jernej.skrabec@siol.net>
+ */
+
+#include <linux/clk-provider.h>
+
+#include "sun8i_dw_hdmi.h"
+
+struct sun8i_phy_clk {
+	struct clk_hw		hw;
+	struct sun8i_hdmi_phy	*phy;
+};
+
+static inline struct sun8i_phy_clk *hw_to_phy_clk(struct clk_hw *hw)
+{
+	return container_of(hw, struct sun8i_phy_clk, hw);
+}
+
+static int sun8i_phy_clk_determine_rate(struct clk_hw *hw,
+					struct clk_rate_request *req)
+{
+	unsigned long rate = req->rate;
+	unsigned long best_rate = 0;
+	struct clk_hw *parent;
+	int best_div = 1;
+	int i;
+
+	parent = clk_hw_get_parent(hw);
+
+	for (i = 1; i <= 16; i++) {
+		unsigned long ideal = rate * i;
+		unsigned long rounded;
+
+		rounded = clk_hw_round_rate(parent, ideal);
+
+		if (rounded == ideal) {
+			best_rate = rounded;
+			best_div = i;
+			break;
+		}
+
+		if (!best_rate ||
+		    abs(rate - rounded / i) <
+		    abs(rate - best_rate / best_div)) {
+			best_rate = rounded;
+			best_div = i;
+		}
+	}
+
+	req->rate = best_rate / best_div;
+	req->best_parent_rate = best_rate;
+	req->best_parent_hw = parent;
+
+	return 0;
+}
+
+static unsigned long sun8i_phy_clk_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	struct sun8i_phy_clk *priv = hw_to_phy_clk(hw);
+	u32 reg;
+
+	regmap_read(priv->phy->regs, SUN8I_HDMI_PHY_PLL_CFG2_REG, &reg);
+	reg = ((reg >> SUN8I_HDMI_PHY_PLL_CFG2_PREDIV_SHIFT) &
+		SUN8I_HDMI_PHY_PLL_CFG2_PREDIV_MSK) + 1;
+
+	return parent_rate / reg;
+}
+
+static int sun8i_phy_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct sun8i_phy_clk *priv = hw_to_phy_clk(hw);
+	unsigned long best_rate = 0;
+	u8 best_m = 0, m;
+
+	for (m = 1; m <= 16; m++) {
+		unsigned long tmp_rate = parent_rate / m;
+
+		if (tmp_rate > rate)
+			continue;
+
+		if (!best_rate ||
+		    (rate - tmp_rate) < (rate - best_rate)) {
+			best_rate = tmp_rate;
+			best_m = m;
+		}
+	}
+
+	regmap_update_bits(priv->phy->regs, SUN8I_HDMI_PHY_PLL_CFG2_REG,
+			   SUN8I_HDMI_PHY_PLL_CFG2_PREDIV_MSK,
+			   SUN8I_HDMI_PHY_PLL_CFG2_PREDIV(best_m));
+
+	return 0;
+}
+
+static const struct clk_ops sun8i_phy_clk_ops = {
+	.determine_rate	= sun8i_phy_clk_determine_rate,
+	.recalc_rate	= sun8i_phy_clk_recalc_rate,
+	.set_rate	= sun8i_phy_clk_set_rate,
+};
+
+int sun8i_phy_clk_create(struct sun8i_hdmi_phy *phy, struct device *dev)
+{
+	struct clk_init_data init;
+	struct sun8i_phy_clk *priv;
+	const char *parents[1];
+
+	parents[0] = __clk_get_name(phy->clk_pll0);
+	if (!parents[0])
+		return -ENODEV;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	init.name = "hdmi-phy-clk";
+	init.ops = &sun8i_phy_clk_ops;
+	init.parent_names = parents;
+	init.num_parents = 1;
+	init.flags = CLK_SET_RATE_PARENT;
+
+	priv->phy = phy;
+	priv->hw.init = &init;
+
+	phy->clk_phy = devm_clk_register(dev, &priv->hw);
+	if (IS_ERR(phy->clk_phy))
+		return PTR_ERR(phy->clk_phy);
+
+	return 0;
+}