[PATCHv3 1/8] devfreq: exynos: Add generic exynos memory bus frequency driver

On 01/13/2015 06:07 PM, MyungJoo Ham wrote:

quoted

 
Dear Myungjoo,

On 01/13/2015 05:42 PM, MyungJoo Ham wrote:

quoted

quoted

  
 This patch adds the generic exynos bus frequency driver for memory bus
with DEVFREQ framework. The Samsung Exynos SoCs have the common architecture
for memory bus between DRAM memory and MMC/sub IP in SoC. This driver can
support the memory bus frequency driver for Exynos SoCs.

Each memory bus block has a clock for memory bus speed and frequency
table which is changed according to the utilization of memory bus on runtime.
And then each memory bus group has the one more memory bus blocks and
OPP table (including frequency and voltage), regulator, devfreq-event
devices.

There are a little difference about the number of memory bus because each Exynos
SoC have the different sub-IP and different memory bus speed. In spite of this
difference among Exynos SoCs, we can support almost Exynos SoC by adding
unique data of memory bus to devicetree file.

Cc: Myungjoo Ham <myungjoo.ham@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Kukjin Kim <kgene@kernel.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
---
 drivers/devfreq/Kconfig          |  15 +
 drivers/devfreq/Makefile         |   1 +
 drivers/devfreq/exynos-busfreq.c | 589 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 605 insertions(+)
 create mode 100644 drivers/devfreq/exynos-busfreq.c

Exynos drivers are located at drivers/devfreq/exynos/
Please relocate/rename exynos-busfreq.c

OK. I'll move it at drivers/devfreq/exynos directory.
Do you prefer 'exynos-bus.c' instead of 'exynos-busfreq.c'?
If you reply, I'll change it.

exynos-bus looks more pretty :)

OK, I'll change the driver name according to your comment.

Best Regards,
Chanwoo Choi

quoted

quoted

[]

quoted

diff --git a/drivers/devfreq/exynos-busfreq.c b/drivers/devfreq/exynos-busfreq.c
new file mode 100644
index 0000000..b180f43
--- /dev/null
+++ b/drivers/devfreq/exynos-busfreq.c

[]

quoted

+
+#define BUS_SATURATION_RATIO	40

In order to be a common driver, this should be tunable.

Because .dts is supposed to have hardware configuration only,
you may keep a table of { chip-name, saturation ratio} in this
driver and look up the saturation ratio based on the chip-name.

OK, I'll add new property for saturation_ratio.

I'll implement to use default saturation_ratio value ,
if dt node don't include saturation_ratio property.

Yes. I didn't talk with DT maintainers and I do not have much
experience with DT; however, it appears that such values are not
recommended to be in DTS files and this value is determined by
the SoC model number without complications in the driver file.