[PATCH] clk: mvebu: Add corediv clock driver for Armada 370/XP

[Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>]

Newer Marvell MVEBU SoC like Armada 370/XP have an additional core
clock divider for e.g. NAND clock. Add the corresponding driver based
on the Linux driver.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
---
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Cc: barebox@lists.infradead.org
---
 drivers/clk/mvebu/Makefile  |   4 +-
 drivers/clk/mvebu/corediv.c | 262 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 264 insertions(+), 2 deletions(-)
 create mode 100644 drivers/clk/mvebu/corediv.c

diff --git a/drivers/clk/mvebu/Makefile b/drivers/clk/mvebu/Makefile
index 6255a5f56d6b..4b2c3c84311b 100644
--- a/drivers/clk/mvebu/Makefile
+++ b/drivers/clk/mvebu/Makefile
@@ -1,5 +1,5 @@
 obj-y				+= common.o
-obj-$(CONFIG_ARCH_ARMADA_370)	+= armada-370.o
-obj-$(CONFIG_ARCH_ARMADA_XP)	+= armada-xp.o
+obj-$(CONFIG_ARCH_ARMADA_370)	+= armada-370.o corediv.o
+obj-$(CONFIG_ARCH_ARMADA_XP)	+= armada-xp.o corediv.o
 obj-$(CONFIG_ARCH_DOVE)		+= dove.o
 obj-$(CONFIG_ARCH_KIRKWOOD)	+= kirkwood.o
diff --git a/drivers/clk/mvebu/corediv.c b/drivers/clk/mvebu/corediv.c
new file mode 100644
index 000000000000..55f6e6ad62e8
--- /dev/null
+++ b/drivers/clk/mvebu/corediv.c
@@ -0,0 +1,262 @@
+/*
+ * MVEBU Core divider clock
+ *
+ * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
+ *
+ * Based on Linux driver
+ *   Copyright (C) 2013 Marvell
+ *   Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <common.h>
+#include <init.h>
+#include <io.h>
+#include <of.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/clkdev.h>
+
+/*
+ * This structure describes the hardware details (bit offset and mask)
+ * to configure one particular core divider clock. Those hardware
+ * details may differ from one SoC to another. This structure is
+ * therefore typically instantiated statically to describe the
+ * hardware details.
+ */
+struct clk_corediv_desc {
+	unsigned int mask;
+	unsigned int offset;
+	unsigned int fieldbit;
+};
+
+/*
+ * This structure describes the hardware details to configure the core
+ * divider clocks on a given SoC. Amongst others, it points to the
+ * array of core divider clock descriptors for this SoC, as well as
+ * the corresponding operations to manipulate them.
+ */
+struct clk_corediv_soc_desc {
+	const struct clk_corediv_desc *descs;
+	unsigned int ndescs;
+	const struct clk_ops ops;
+	u32 ratio_reload;
+	u32 enable_bit_offset;
+	u32 ratio_offset;
+};
+
+/*
+ * This structure represents one core divider clock for the clock
+ * framework, and is dynamically allocated for each core divider clock
+ * existing in the current SoC.
+ */
+struct clk_corediv {
+	struct clk clk;
+	void __iomem *reg;
+	const struct clk_corediv_desc *desc;
+	const struct clk_corediv_soc_desc *soc_desc;
+};
+
+static struct clk_onecell_data clk_data;
+
+/*
+ * Description of the core divider clocks available. For now, we
+ * support only NAND, and it is available at the same register
+ * locations regardless of the SoC.
+ */
+static const struct clk_corediv_desc mvebu_corediv_desc[] = {
+	{ .mask = 0x3f, .offset = 8, .fieldbit = 1 }, /* NAND clock */
+};
+
+#define CORE_CLK_DIV_RATIO_MASK	0xff
+
+#define to_corediv_clk(p) container_of(p, struct clk_corediv, clk)
+
+static int clk_corediv_is_enabled(struct clk *clk)
+{
+	struct clk_corediv *corediv = to_corediv_clk(clk);
+	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
+	const struct clk_corediv_desc *desc = corediv->desc;
+	u32 enable_mask = BIT(desc->fieldbit) << soc_desc->enable_bit_offset;
+
+	return !!(readl(corediv->reg) & enable_mask);
+}
+
+static int clk_corediv_enable(struct clk *clk)
+{
+	struct clk_corediv *corediv = to_corediv_clk(clk);
+	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
+	const struct clk_corediv_desc *desc = corediv->desc;
+	u32 reg;
+
+	reg = readl(corediv->reg);
+	reg |= (BIT(desc->fieldbit) << soc_desc->enable_bit_offset);
+	writel(reg, corediv->reg);
+
+	return 0;
+}
+
+static void clk_corediv_disable(struct clk *clk)
+{
+	struct clk_corediv *corediv = to_corediv_clk(clk);
+	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
+	const struct clk_corediv_desc *desc = corediv->desc;
+	u32 reg;
+
+	reg = readl(corediv->reg);
+	reg &= ~(BIT(desc->fieldbit) << soc_desc->enable_bit_offset);
+	writel(reg, corediv->reg);
+}
+
+static unsigned long clk_corediv_recalc_rate(struct clk *clk,
+					     unsigned long parent_rate)
+{
+	struct clk_corediv *corediv = to_corediv_clk(clk);
+	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
+	const struct clk_corediv_desc *desc = corediv->desc;
+	u32 reg, div;
+
+	reg = readl(corediv->reg + soc_desc->ratio_offset);
+	div = (reg >> desc->offset) & desc->mask;
+	return parent_rate / div;
+}
+
+static long clk_corediv_round_rate(struct clk *clk, unsigned long rate,
+				   unsigned long *parent_rate)
+{
+	/* Valid ratio are 1:4, 1:5, 1:6 and 1:8 */
+	u32 div;
+
+	div = *parent_rate / rate;
+	if (div < 4)
+		div = 4;
+	else if (div > 6)
+		div = 8;
+
+	return *parent_rate / div;
+}
+
+static int clk_corediv_set_rate(struct clk *clk, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct clk_corediv *corediv = to_corediv_clk(clk);
+	const struct clk_corediv_soc_desc *soc_desc = corediv->soc_desc;
+	const struct clk_corediv_desc *desc = corediv->desc;
+	u32 reg, div;
+
+	div = parent_rate / rate;
+
+	/* Write new divider to the divider ratio register */
+	reg = readl(corediv->reg + soc_desc->ratio_offset);
+	reg &= ~(desc->mask << desc->offset);
+	reg |= (div & desc->mask) << desc->offset;
+	writel(reg, corediv->reg + soc_desc->ratio_offset);
+
+	/* Set reload-force for this clock */
+	reg = readl(corediv->reg) | BIT(desc->fieldbit);
+	writel(reg, corediv->reg);
+
+	/* Now trigger the clock update */
+	reg = readl(corediv->reg) | soc_desc->ratio_reload;
+	writel(reg, corediv->reg);
+
+	/*
+	 * Wait for clocks to settle down, and then clear all the
+	 * ratios request and the reload request.
+	 */
+	udelay(1000);
+	reg &= ~(CORE_CLK_DIV_RATIO_MASK | soc_desc->ratio_reload);
+	writel(reg, corediv->reg);
+	udelay(1000);
+
+	return 0;
+}
+
+static const struct clk_corediv_soc_desc armada370_corediv_soc = {
+	.descs = mvebu_corediv_desc,
+	.ndescs = ARRAY_SIZE(mvebu_corediv_desc),
+	.ops = {
+		.enable = clk_corediv_enable,
+		.disable = clk_corediv_disable,
+		.is_enabled = clk_corediv_is_enabled,
+		.recalc_rate = clk_corediv_recalc_rate,
+		.round_rate = clk_corediv_round_rate,
+		.set_rate = clk_corediv_set_rate,
+	},
+	.ratio_reload = BIT(8),
+	.enable_bit_offset = 24,
+	.ratio_offset = 0x8,
+};
+
+static struct of_device_id mvebu_corediv_clk_ids[] = {
+	{ .compatible = "marvell,armada-370-corediv-clock",
+	  .data = &armada370_corediv_soc },
+	{ }
+};
+
+static int mvebu_corediv_clk_probe(struct device_d *dev)
+{
+	struct device_node *np = dev->device_node;
+	const struct of_device_id *match;
+	const struct clk_corediv_soc_desc *soc_desc;
+	struct clk_corediv *corediv;
+	struct clk *parent;
+	void __iomem *base;
+	int n;
+
+	match = of_match_node(mvebu_corediv_clk_ids, np);
+	if (!match)
+		return -EINVAL;
+	soc_desc = (const struct clk_corediv_soc_desc *)match->data;
+
+	base = dev_request_mem_region(dev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	parent = of_clk_get(np, 0);
+	if (IS_ERR(parent))
+		return PTR_ERR(parent);
+
+	clk_data.clk_num = soc_desc->ndescs;
+	clk_data.clks = xzalloc(clk_data.clk_num * sizeof(*clk_data.clks));
+	corediv = xzalloc(clk_data.clk_num * sizeof(*corediv));
+
+	for (n = 0; n < clk_data.clk_num; n++) {
+		const char *clk_name;
+		struct clk *clk = &corediv->clk;
+
+		if (of_property_read_string_index(np,
+				"clock-output-names", n, &clk_name)) {
+			dev_warn(dev, "missing clock output name %d\n", n);
+			continue;
+		}
+
+		clk->ops = &soc_desc->ops;
+		clk->name = clk_name;
+		clk->flags = 0;
+		clk->parent_names = &parent->name;
+		clk->num_parents = 1;
+		corediv->soc_desc = soc_desc;
+		corediv->desc = &soc_desc->descs[n];
+		corediv->reg = base;
+		clk_data.clks[n] = clk;
+		WARN_ON(IS_ERR_VALUE(clk_register(clk)));
+	}
+
+	return of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
+}
+
+static struct driver_d mvebu_corediv_clk_driver = {
+	.probe	= mvebu_corediv_clk_probe,
+	.name	= "mvebu-corediv-clk",
+	.of_compatible = DRV_OF_COMPAT(mvebu_corediv_clk_ids),
+};
+
+static int mvebu_corediv_clk_init(void)
+{
+	return platform_driver_register(&mvebu_corediv_clk_driver);
+}
+postcore_initcall(mvebu_corediv_clk_init);
-- 
2.1.0


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