SPEAr: clk: Add VCO-PLL Synthesizer clock

All SPEAr SoC's contain PLLs. Their Fout is derived based on following equations

- In normal mode
  vco = (2 * M[15:8] * Fin)/N

- In Dithered mode
  vco = (2 * M[15:0] * Fin)/(256 * N)

pll_rate = vco/2^p

vco and pll are very closely bound to each other,
"vco needs to program: mode, m & n" and "pll needs to program p",
both share common enable/disable logic and registers.

This patch adds in support for this type of clock.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Reviewed-by: Mike Turquette <mturquette@linaro.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/drivers/clk/spear/clk.c b/drivers/clk/spear/clk.c
new file mode 100644
index 000000000000..376d4e5ff326
--- /dev/null
+++ b/drivers/clk/spear/clk.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2012 ST Microelectronics
+ * Viresh Kumar <viresh.kumar@st.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.
+ *
+ * SPEAr clk - Common routines
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/types.h>
+#include "clk.h"
+
+long clk_round_rate_index(struct clk_hw *hw, unsigned long drate,
+                unsigned long parent_rate, clk_calc_rate calc_rate, u8 rtbl_cnt,
+                int *index)
+{
+        unsigned long prev_rate, rate = 0;
+
+        for (*index = 0; *index < rtbl_cnt; (*index)++) {
+                prev_rate = rate;
+                rate = calc_rate(hw, parent_rate, *index);
+                if (drate < rate) {
+                        /* previous clock was best */
+                        if (*index) {
+                                rate = prev_rate;
+                                (*index)--;
+                        }
+                        break;
+                }
+        }
+
+        return rate;
+}