Add a generic helper function to compute PLL parameters for PLL found in
several Aptina sensors.
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
drivers/media/video/Kconfig | 4 +
drivers/media/video/Makefile | 4 +
drivers/media/video/aptina-pll.c | 120 ++++++++++++++++++++++++++++++++++++++
drivers/media/video/aptina-pll.h | 55 +++++++++++++++++
4 files changed, 183 insertions(+), 0 deletions(-)
create mode 100644 drivers/media/video/aptina-pll.c
create mode 100644 drivers/media/video/aptina-pll.h
diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
index 02afc02..b255c29 100644
--- a/drivers/media/video/Kconfig
+++ b/drivers/media/video/Kconfig
@@ -133,6 +133,9 @@ menu "Encoders, decoders, sensors and other helper chips"
comment "Audio decoders, processors and mixers"
+config VIDEO_APTINA_PLL
+ tristate
+
config VIDEO_TVAUDIO
tristate "Simple audio decoder chips"
depends on VIDEO_V4L2 && I2C
@@ -946,6 +949,7 @@ config SOC_CAMERA_MT9M001
config VIDEO_MT9M032
tristate "MT9M032 camera sensor support"
depends on I2C && VIDEO_V4L2
+ select VIDEO_APTINA_PLL
help
This driver supports MT9M032 cameras from Micron, monochrome
models only.
diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
index 2fa78d6..06d33ed 100644
--- a/drivers/media/video/Makefile
+++ b/drivers/media/video/Makefile
@@ -22,6 +22,10 @@ endif
obj-$(CONFIG_VIDEO_V4L2_COMMON) += v4l2-common.o
+# Helper modules
+
+obj-$(CONFIG_VIDEO_APTINA_PLL) += aptina-pll.o
+
# All i2c modules must come first:
obj-$(CONFIG_VIDEO_TUNER) += tuner.o
diff --git a/drivers/media/video/aptina-pll.c b/drivers/media/video/aptina-pll.c
new file mode 100644
index 0000000..e4df9ec
--- /dev/null
+++ b/drivers/media/video/aptina-pll.c
@@ -0,0 +1,120 @@
+/*
+ * Aptina Sensor PLL Configuration
+ *
+ * Copyright (C) 2012 Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/device.h>
+#include <linux/gcd.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include "aptina-pll.h"
+
+int aptina_pll_configure(struct device *dev, struct aptina_pll *pll,
+ const struct aptina_pll_limits *limits)
+{
+ unsigned int mf_min;
+ unsigned int mf_max;
+ unsigned int mf;
+ unsigned int clock;
+ unsigned int div;
+ unsigned int p1;
+ unsigned int n;
+ unsigned int m;
+
+ if (pll->ext_clock < limits->ext_clock_min ||
+ pll->ext_clock > limits->ext_clock_max) {
+ dev_err(dev, "pll: invalid external clock frequency.\n");
+ return -EINVAL;
+ }
+
+ if (pll->pix_clock > limits->pix_clock_max) {
+ dev_err(dev, "pll: invalid pixel clock frequency.\n");
+ return -EINVAL;
+ }
+
+ /* Compute the multiplier M and combined N*P1 divisor. */
+ div = gcd(pll->pix_clock, pll->ext_clock);
+ pll->m = pll->pix_clock / div;
+ div = pll->ext_clock / div;
+
+ /* We now have the smallest M and N*P1 values that will result in the
+ * desired pixel clock frequency, but they might be out of the valid
+ * range. Compute the factor by which we should multiply them given the
+ * following constraints:
+ *
+ * - minimum/maximum multiplier
+ * - minimum/maximum multiplier output clock frequency assuming the
+ * minimum/maximum N value
+ * - minimum/maximum combined N*P1 divisor
+ */
+ mf_min = DIV_ROUND_UP(limits->m_min, pll->m);
+ mf_min = max(mf_min, limits->out_clock_min /
+ (pll->ext_clock / limits->n_min * pll->m));
+ mf_min = max(mf_min, limits->n_min * limits->p1_min / div);
+ mf_max = limits->m_max / pll->m;
+ mf_max = min(mf_max, limits->out_clock_max /
+ (pll->ext_clock / limits->n_max * pll->m));
+ mf_max = min(mf_max, DIV_ROUND_UP(limits->n_max * limits->p1_max, div));
+
+ dev_dbg(dev, "pll: mf min %u max %u\n", mf_min, mf_max);
+ if (mf_min > mf_max) {
+ dev_err(dev, "pll: no valid combined N*P1 divisor.\n");
+ return -EINVAL;
+ }
+
+ /* Find the highest acceptable P1 value and compute the corresponding N
+ * divisor. Make sure the P1 value is even.
+ */
+ for (mf = mf_min; mf <= mf_max; ++mf) {
+ m = pll->m * mf;
+
+ for (p1 = limits->p1_max & ~1; p1 > limits->p1_min; p1 -= 2) {
+ if ((div * mf) % p1)
+ continue;
+
+ n = div * mf / p1;
+
+ clock = pll->ext_clock / n;
+ if (clock < limits->int_clock_min ||
+ clock > limits->int_clock_max)
+ continue;
+
+ clock *= m;
+ if (clock < limits->out_clock_min ||
+ clock > limits->out_clock_max)
+ continue;
+
+ goto found;
+ }
+ }
+
+ dev_err(dev, "pll: no valid N and P1 divisors found.\n");
+ return -EINVAL;
+
+found:
+ pll->n = n;
+ pll->m = m;
+ pll->p1 = p1;
+
+ dev_dbg(dev, "PLL: ext clock %u N %u M %u P1 %u pix clock %u\n",
+ pll->ext_clock, pll->n, pll->m, pll->p1, pll->pix_clock);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(aptina_pll_configure);
diff --git a/drivers/media/video/aptina-pll.h b/drivers/media/video/aptina-pll.h
new file mode 100644
index 0000000..36a9363
--- /dev/null
+++ b/drivers/media/video/aptina-pll.h
@@ -0,0 +1,55 @@
+/*
+ * Aptina Sensor PLL Configuration
+ *
+ * Copyright (C) 2012 Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef __APTINA_PLL_H
+#define __APTINA_PLL_H
+
+struct aptina_pll {
+ unsigned int ext_clock;
+ unsigned int pix_clock;
+
+ unsigned int n;
+ unsigned int m;
+ unsigned int p1;
+};
+
+struct aptina_pll_limits {
+ unsigned int ext_clock_min;
+ unsigned int ext_clock_max;
+ unsigned int int_clock_min;
+ unsigned int int_clock_max;
+ unsigned int out_clock_min;
+ unsigned int out_clock_max;
+ unsigned int pix_clock_max;
+
+ unsigned int n_min;
+ unsigned int n_max;
+ unsigned int m_min;
+ unsigned int m_max;
+ unsigned int p1_min;
+ unsigned int p1_max;
+};
+
+struct device;
+
+int aptina_pll_configure(struct device *dev, struct aptina_pll *pll,
+ const struct aptina_pll_limits *limits);
+
+#endif /* __APTINA_PLL_H */
--
1.7.3.4
--
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