Messages in this thread | | | From | Soren Brinkmann <> | Subject | [PATCH RFC 0/3] clk: CCF clock primitives + custom IO accessors | Date | Fri, 28 Feb 2014 15:34:52 -0800 |
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Hi,
I recently ran into a problem which seems to become common. I was trying to write a driver for the TI CDCE913, a programmable clock synthesizer on the I2C bus. Internally that device consists of a PLL and a bunch of muxes, gates and dividers that eventually end up in three clock outputs. Looking at that device, it seems rather easy to model it with the available clock primitives, the problem though is, the clock primitives assume accesses via memory mapped IO.
To overcome a similar problem the PPC folks introduced the clk_(read|write)l wrappers, which seems to go into the right direction, but that also only allows per ARCH overrides. I.e. wouldn't allow mixing of MMIO clocks and clocks using I2C via regmap or similar.
So, the first thing I did, was essentially duplicating the clock primitives I need and simply replacing the readl/writel with regmap_read/write. So there is a lot of code duplication to use all the fancy features the clk-mux and clk-div primitives provide, just to replace the IO access.
In the next step, I encountered a divider clock whose divider is stored in 2 I2C registers. So now, the simple IO access replacement doesn't work anymore either since this clock needs 2 registers to be read and then shifting around the bitfields accordingly.
Does anybody have a good idea how we could avoid all this code duplication while enabling usage of the clock primitives with different IO accessors? Especially the divider and mux primitive have a lot of code that would be painful to maintain twice.
Thanks, Sören
Soren Brinkmann (3): clk: Introduce I2C clock primitives clk/i2c-div: Allow custom divider accessors clk: Add driver for TI CDCE913
.../devicetree/bindings/clock/ti,cdce913.txt | 32 + drivers/clk/Kconfig | 15 + drivers/clk/Makefile | 6 + drivers/clk/clk-cdce913.c | 841 +++++++++++++++++++++ drivers/clk/clk-i2c-divider.c | 375 +++++++++ drivers/clk/clk-i2c-mux.c | 173 +++++ drivers/clk/clk-i2c.c | 22 + include/linux/clk-provider.h | 104 +++ 8 files changed, 1568 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/ti,cdce913.txt create mode 100644 drivers/clk/clk-cdce913.c create mode 100644 drivers/clk/clk-i2c-divider.c create mode 100644 drivers/clk/clk-i2c-mux.c create mode 100644 drivers/clk/clk-i2c.c
-- 1.9.0.1.g4196000
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