Hi,

On Thu, Jun 09, 2016 at 09:41:01AM +0200, Jean-Francois Moine wrote:

On Tue,  7 Jun 2016 22:41:50 +0200
Maxime Ripard [off-list ref] wrote:

quoted

Introduce support for clocks that multiply and divide using linear factors.

Signed-off-by: Maxime Ripard <redacted>

---
Changes from v1:
  - Fixed the maximums for both factors passed to the rational factor
    computation.
---
 drivers/clk/sunxi-ng/Makefile |   1 +
 drivers/clk/sunxi-ng/ccu_nm.c | 114 ++++++++++++++++++++++++++++++++++++++++++
 drivers/clk/sunxi-ng/ccu_nm.h |  95 +++++++++++++++++++++++++++++++++++
 3 files changed, 210 insertions(+)
 create mode 100644 drivers/clk/sunxi-ng/ccu_nm.c
 create mode 100644 drivers/clk/sunxi-ng/ccu_nm.h

diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile
index a201fad6b11d..5c7ae1ad1082 100644
--- a/drivers/clk/sunxi-ng/Makefile
+++ b/drivers/clk/sunxi-ng/Makefile

@@ -9,4 +9,5 @@ obj-y += ccu_gate.o
 obj-y += ccu_mp.o
 obj-y += ccu_mux.o
 obj-y += ccu_nk.o
+obj-y += ccu_nm.o
 obj-y += ccu_phase.o

diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
new file mode 100644
index 000000000000..e35ddd8eec8b
--- /dev/null
+++ b/drivers/clk/sunxi-ng/ccu_nm.c

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2016 Maxime Ripard
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * 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.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/rational.h>
+
+#include "ccu_frac.h"
+#include "ccu_gate.h"
+#include "ccu_nm.h"

	[snip]

quoted

+static unsigned long ccu_nm_recalc_rate(struct clk_hw *hw,
+					unsigned long parent_rate)
+{
+	struct ccu_nm *nm = hw_to_ccu_nm(hw);
+	unsigned long n, m;
+	u32 reg;
+
+	if (ccu_frac_helper_is_enabled(&nm->common, &nm->frac))
+		return ccu_frac_helper_read_rate(&nm->common, &nm->frac);
+
+	reg = readl(nm->common.base + nm->common.reg);
+
+	n = reg >> nm->n.shift;
+	n &= (1 << nm->n.width) - 1;
+
+	m = reg >> nm->m.shift;
+	m &= (1 << nm->m.width) - 1;
+
+	return parent_rate * (n + 1) / (m + 1);

In the H3, 'm' is a pre-divider (audio and video PLLs):

	return parent_rate / (m + 1) * (n + 1);

That's true, but the "true" N-M clocks exist and are using this
formula (like the Audio PLL on A10's).

If (and when) that causes some rounding issues, we can always add
pre-divider support to N-Clocks that we are going to need anyway for
the older SoCs.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20160627/f0177858/attachment.sig>