This patch series brings the files from Linux kernel to provide clocks support as it is used on the Linux kernel with common clock framework [CCF] setup.
This series also fixes several problems with current clocks and provides sandbox tests for functions addded to clk-uclass.c file.
Design decisions/issues: =========================
- U-boot's DM for clk differs from Linux CCF. The most notably difference is the lack of support for hierarchical clocks and "clock as a manager driver" (single clock DTS node acts as a starting point for all other clocks).
- The clk_get_rate() now caches the previously read data (no need for recursive access.
- On purpose the "manager" clk driver (clk-imx6q.c) is not using large table to store pointers to clocks - e.g. clk[IMX6QDL_CLK_USDHC2_SEL] = .... Instead we use udevice's linked list for the same class (UCLASS_CLK). The rationale - when porting the code as is from Linux, one would need ~1KiB of RAM to store it. This is way too much if we do plan to use this driver in SPL.
- The "central" structure of this patch series is struct udevice and its driver_data field contains the struct clk pointer (to the originally created one).
- Up till now U-boot's driver model's CLK operates on udevice (main access to clock is by udevice ops) In the CCF the access to struct clk (comprising pointer to *dev) is possible via dev_get_driver_data()
Storing back pointer (from udevice to struct clk) as driver_data is a convention for CCF.
- I could use *private_alloc_size to allocate driver's 'private" structures (dev->priv) for e.g. divider (struct clk_divider *divider) for IMX6Q clock, but this would change the original structure of the CCF code.
The question is if it would be better to use private_alloc_size (and dev->private) or stay with driver_data. The former requires some rewritting in CCF original code (to remove (c)malloc, etc), but comply with u-boot DM. The latter allows re-using the CCF code as is, but introduces some convention special for CCF (I'm not sure thought if dev->priv is NOT another convention as well).
- I've added the clk_get_parent(), which reads parent's dev->driver_data to provide parent's struct clk pointer. This seems the easiest way to get child/parent relationship for struct clk in U-boot's udevice based clocks.
- For tests I had to "emulate" CCF code structure to test functionality of clk_get_parent_rate() and clk_get_by_id(). Those functions will not work properly with "standard" (i.e. non CCF) clock setup(with not set dev->driver_data to struct clk).
Repository: https://github.com/lmajewski/u-boot-dfu/commits/CCF-v3
Changes in v3: - New patch - The rate information is now cached into struct clk field - The clk_get_parent() is used to get pointer to the parent struct clk - Replace -ENODEV with -ENOENT - Use **clkp instead of **c - New patch - New patch
Lukasz Majewski (11): dm: Fix documentation entry as there is no UCLASS_CLOCK uclass cmd: Do not show frequency for clocks which .get_rate() return error clk: Remove clock ID check in .get_rate() of clk_fixed_* clk: Extend struct clk to provide information regarding clock rate clk: Provide struct clk for fixed rate clock (clk_fixed_rate.c) dm: clk: Define clk_get_parent() for clk operations dm: clk: Define clk_get_parent_rate() for clk operations dm: clk: Define clk_get_by_id() for clk operations clk: test: Provide unit test for clk_get_by_id() method clk: test: Provide unit test for clk_get_parent_rate() method clk: Port Linux common clock framework [CCF] for imx6q to U-boot (tag: 5.0-rc3)
arch/sandbox/include/asm/clk.h | 16 ++++ cmd/clk.c | 5 +- drivers/clk/Kconfig | 14 ++++ drivers/clk/Makefile | 2 + drivers/clk/clk-divider.c | 148 ++++++++++++++++++++++++++++++++++ drivers/clk/clk-fixed-factor.c | 87 ++++++++++++++++++++ drivers/clk/clk-mux.c | 164 +++++++++++++++++++++++++++++++++++++ drivers/clk/clk-uclass.c | 59 ++++++++++++++ drivers/clk/clk.c | 56 +++++++++++++ drivers/clk/clk_fixed_factor.c | 3 - drivers/clk/clk_fixed_rate.c | 8 +- drivers/clk/clk_sandbox_test.c | 49 +++++++++++ drivers/clk/imx/Kconfig | 9 +++ drivers/clk/imx/Makefile | 2 + drivers/clk/imx/clk-gate2.c | 113 ++++++++++++++++++++++++++ drivers/clk/imx/clk-imx6q.c | 179 +++++++++++++++++++++++++++++++++++++++++ drivers/clk/imx/clk-pfd.c | 91 +++++++++++++++++++++ drivers/clk/imx/clk-pllv3.c | 83 +++++++++++++++++++ drivers/clk/imx/clk.h | 75 +++++++++++++++++ include/clk.h | 33 +++++++- include/linux/clk-provider.h | 94 ++++++++++++++++++++++ test/dm/clk.c | 4 +- 22 files changed, 1285 insertions(+), 9 deletions(-) create mode 100644 drivers/clk/clk-divider.c create mode 100644 drivers/clk/clk-fixed-factor.c create mode 100644 drivers/clk/clk-mux.c create mode 100644 drivers/clk/clk.c create mode 100644 drivers/clk/imx/clk-gate2.c create mode 100644 drivers/clk/imx/clk-imx6q.c create mode 100644 drivers/clk/imx/clk-pfd.c create mode 100644 drivers/clk/imx/clk-pllv3.c create mode 100644 drivers/clk/imx/clk.h create mode 100644 include/linux/clk-provider.h