clk: add pxa clocks infrastructure

Add a the common code used by all PXA variants.

This is the first step in the transition from architecture defined
clocks (in arch/arm/mach-pxa) towards clock framework. The goal is to
have the same features (and not all the features) of the existing
clocks, and enable the transition of PXA to device-tree.

All PXA rely on a "CKEN" type clock, which :
 - has a gate (bit in CKEN register)
 - is generated from a PLL, generally divided
 - has an alternate low power clock

Each variant will specialize the CKEN clock :
 - pxa25x have no low power clock
 - pxa27x in low power use always the 13 MHz ring oscillator
 - pxa3xx in low power have specific dividers for each clock

The device-tree provides a list of CLK_* (ex: CLK_USB or CLK_I2C) to get
a handle on the clock. While pxa-clock.h will describe all the clocks of
all the variants, each variant will only use a subset of it.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/pxa/clk-pxa.c

@@ -0,0 +1,97 @@
+/*
+ * Marvell PXA family clocks
+ *
+ * Copyright (C) 2014 Robert Jarzmik
+ *
+ * Common clock code for PXA clocks ("CKEN" type clocks + DT)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ */
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/of.h>
+
+#include <dt-bindings/clock/pxa-clock.h>
+#include "clk-pxa.h"
+
+DEFINE_SPINLOCK(lock);
+
+static struct clk *pxa_clocks[CLK_MAX];
+static struct clk_onecell_data onecell_data = {
+	.clks = pxa_clocks,
+	.clk_num = CLK_MAX,
+};
+
+#define to_pxa_clk(_hw) container_of(_hw, struct pxa_clk_cken, hw)
+
+static unsigned long cken_recalc_rate(struct clk_hw *hw,
+				      unsigned long parent_rate)
+{
+	struct pxa_clk_cken *pclk = to_pxa_clk(hw);
+	struct clk_fixed_factor *fix;
+
+	if (!pclk->is_in_low_power || pclk->is_in_low_power())
+		fix = &pclk->lp;
+	else
+		fix = &pclk->hp;
+	fix->hw.clk = hw->clk;
+	return clk_fixed_factor_ops.recalc_rate(&fix->hw, parent_rate);
+}
+
+static struct clk_ops cken_rate_ops = {
+	.recalc_rate = cken_recalc_rate,
+};
+
+static u8 cken_get_parent(struct clk_hw *hw)
+{
+	struct pxa_clk_cken *pclk = to_pxa_clk(hw);
+
+	if (!pclk->is_in_low_power)
+		return 0;
+	return pclk->is_in_low_power() ? 0 : 1;
+}
+
+static struct clk_ops cken_mux_ops = {
+	.get_parent = cken_get_parent,
+	.set_parent = dummy_clk_set_parent,
+};
+
+void __init clkdev_pxa_register(int ckid, const char *con_id,
+				const char *dev_id, struct clk *clk)
+{
+	if (!IS_ERR(clk) && (ckid != CLK_NONE))
+		pxa_clocks[ckid] = clk;
+	if (!IS_ERR(clk))
+		clk_register_clkdev(clk, con_id, dev_id);
+}
+
+int __init clk_pxa_cken_init(struct pxa_clk_cken *clks, int nb_clks)
+{
+	int i;
+	struct pxa_clk_cken *pclk;
+	struct clk *clk;
+
+	for (i = 0; i < nb_clks; i++) {
+		pclk = clks + i;
+		pclk->gate.lock = &lock;
+		clk = clk_register_composite(NULL, pclk->name,
+					     pclk->parent_names, 2,
+					     &pclk->hw, &cken_mux_ops,
+					     &pclk->hw, &cken_rate_ops,
+					     &pclk->gate.hw, &clk_gate_ops,
+					     pclk->flags);
+		clkdev_pxa_register(pclk->ckid, pclk->con_id, pclk->dev_id,
+				    clk);
+	}
+	return 0;
+}
+
+static void __init pxa_dt_clocks_init(struct device_node *np)
+{
+	of_clk_add_provider(np, of_clk_src_onecell_get, &onecell_data);
+}
+CLK_OF_DECLARE(pxa_clks, "marvell,pxa-clocks", pxa_dt_clocks_init);