clk: sunxi: Add sun8i MBUS clock support

The MBUS clock on sun8i is slightly different from the old mod0 clocks.
The divider is 3 bits wider, while also needing a divider table for the
higher 4 values, which all set the same divider.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/drivers/clk/sunxi/clk-sun8i-mbus.c b/drivers/clk/sunxi/clk-sun8i-mbus.c
new file mode 100644
index 000000000000..8e49b44cee41
--- /dev/null
+++ b/drivers/clk/sunxi/clk-sun8i-mbus.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2014 Chen-Yu Tsai
+ *
+ * Chen-Yu Tsai <wens@csie.org>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/of_address.h>
+
+#include "clk-factors.h"
+
+/**
+ * sun8i_a23_get_mbus_factors() - calculates m factor for MBUS clocks
+ * MBUS rate is calculated as follows
+ * rate = parent_rate / (m + 1);
+ */
+
+static void sun8i_a23_get_mbus_factors(u32 *freq, u32 parent_rate,
+                                       u8 *n, u8 *k, u8 *m, u8 *p)
+{
+        u8 div;
+
+        /*
+         * These clocks can only divide, so we will never be able to
+         * achieve frequencies higher than the parent frequency
+         */
+        if (*freq > parent_rate)
+                *freq = parent_rate;
+
+        div = DIV_ROUND_UP(parent_rate, *freq);
+
+        if (div > 8)
+                div = 8;
+
+        *freq = parent_rate / div;
+
+        /* we were called to round the frequency, we can now return */
+        if (m == NULL)
+                return;
+
+        *m = div - 1;
+}
+
+static struct clk_factors_config sun8i_a23_mbus_config = {
+        .mshift = 0,
+        .mwidth = 3,
+};
+
+static const struct factors_data sun8i_a23_mbus_data __initconst = {
+        .enable = 31,
+        .mux = 24,
+        .table = &sun8i_a23_mbus_config,
+        .getter = sun8i_a23_get_mbus_factors,
+};
+
+static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
+
+static void __init sun8i_a23_mbus_setup(struct device_node *node)
+{
+        struct clk *mbus = sunxi_factors_register(node, &sun8i_a23_mbus_data,
+                                                  &sun8i_a23_mbus_lock);
+
+        /* The MBUS clocks needs to be always enabled */
+        __clk_get(mbus);
+        clk_prepare_enable(mbus);
+}
+CLK_OF_DECLARE(sun8i_a23_mbus, "allwinner,sun8i-a23-mbus-clk", sun8i_a23_mbus_setup);