kernel/drivers/clk/tegra/clk.h, branch linux-6.9.y

clk: tegra: Support runtime PM and power domain

2021-12-15T17:55:21Z

The Clock-and-Reset controller resides in a core power domain on NVIDIA Tegra SoCs. In order to support voltage scaling of the core power domain, we hook up DVFS-capable clocks to the core GENPD for managing of the GENPD's performance state based on the clock changes. Some clocks don't have any specific physical hardware unit that backs them, like root PLLs and system clock and they have theirs own voltage requirements. This patch adds new clk-device driver that backs the clocks and provides runtime PM functionality for them. A virtual clk-device is created for each such DVFS-capable clock at the clock's registration time by the new tegra_clk_register() helper. Driver changes clock's device GENPD performance state based on clk-rate notifications. In result we have this sequence of events: 1. Clock driver creates virtual device for selective clocks, enables runtime PM for the created device and registers the clock. 2. Clk-device driver starts to listen to clock rate changes. 3. Something changes clk rate or enables/disables clk. 4. CCF core propagates the change through the clk tree. 5. Clk-device driver gets clock rate-change notification or GENPD core handles prepare/unprepare of the clock. 6. Clk-device driver changes GENPD performance state on clock rate change. 7. GENPD driver changes voltage regulator state change. 8. The regulator state is committed to hardware via I2C. We rely on fact that DVFS is not needed for Tegra I2C and that Tegra I2C driver already keeps clock always-prepared. Hence I2C subsystem stays independent from the clk power management and there are no deadlock spots in the sequence. Currently all clocks are registered very early during kernel boot when the device driver core isn't available yet. The clk-device can't be created at that time. This patch splits the registration of the clocks in two phases: 1. Register all essential clocks which don't use RPM and are needed during early boot. 2. Register at a later boot time the rest of clocks. This patch adds power management support for Tegra20 and Tegra30 clocks. Reviewed-by: Ulf Hansson Tested-by: Peter Geis # Ouya T30 Tested-by: Paul Fertser # PAZ00 T20 Tested-by: Nicolas Chauvet # PAZ00 T20 and TK1 T124 Tested-by: Matt Merhar # Ouya T30 Signed-off-by: Dmitry Osipenko Signed-off-by: Thierry Reding

clk: tegra: Don't deassert reset on enabling clocks

2021-05-31T13:16:46Z

The Tegra clock driver contains legacy code which deasserts hardware reset when peripheral clocks are enabled. This behaviour comes from a pre-CCF era of the Tegra drivers. This is unacceptable for modern kernel drivers which use generic CCF and reset-control APIs because it breaks assumptions of the drivers about clk/reset sequences and about reset-propagation delays. Hence remove the awkward legacy behaviour from the clk driver. In particular PMC driver assumes that hardware blocks remains in reset while power domain is turning on, but the clk driver deasserts the reset before power clamp is removed, hence breaking the driver's assumption. Signed-off-by: Dmitry Osipenko Signed-off-by: Thierry Reding

memory: tegra124-emc: Make driver modular

2021-01-05T17:00:09Z

Add modularization support to the Tegra124 EMC driver, which now can be compiled as a loadable kernel module. Note that EMC clock must be registered at clk-init time, otherwise PLLM will be disabled as unused clock at boot time if EMC driver is compiled as a module. Hence add a prepare/complete callbacks. similarly to what is done for the Tegra20/30 EMC drivers. Tested-by: Nicolas Chauvet Signed-off-by: Dmitry Osipenko Link: https://lore.kernel.org/r/20201228154920.18846-2-digetx@gmail.com Signed-off-by: Krzysztof Kozlowski

clk: tegra: cclk: Add helpers for handling PLLX rate changes

2020-05-12T20:48:43Z

CCLK should be re-parented away from PLLX if PLLX's rate is changing. The PLLP parent is a common safe CPU parent for all Tegra SoCs, thus CCLK will be re-parented to PLLP before PLLX rate-change begins and then switched back to PLLX after the rate-change completion. This patch adds helper functions which perform CCLK re-parenting, these helpers will be utilized by further patches. Acked-by: Peter De Schrijver Tested-by: Peter Geis Tested-by: Marcel Ziswiler Tested-by: Jasper Korten Tested-by: David Heidelberg Tested-by: Nicolas Chauvet Signed-off-by: Dmitry Osipenko Signed-off-by: Thierry Reding

clk: tegra: pll: Add pre/post rate-change hooks

2020-05-12T20:48:42Z

There is a need to temporarily re-parent CCLK away from PLLX if PLLX's rate is about to change. The newly introduced PLL pre/post rate-change hooks allow to handle such case. Acked-by: Peter De Schrijver Tested-by: Peter Geis Tested-by: Marcel Ziswiler Tested-by: Jasper Korten Tested-by: David Heidelberg Tested-by: Nicolas Chauvet Signed-off-by: Dmitry Osipenko Signed-off-by: Thierry Reding

clk: tegra: Add custom CCLK implementation

2020-05-12T20:48:42Z

CCLK stands for "CPU Clock", CPU core is running off CCLK. CCLK supports multiple parents, it has internal clock divider and a clock skipper. PLLX is the main CCLK parent that provides clock rates above 1GHz and it has special property such that the CCLK's internal divider is set into bypass mode when PLLX is selected as a parent for CCLK. This patch forks generic Super Clock into CCLK implementation which takes into account all CCLK specifics. The proper CCLK implementation is needed by the upcoming Tegra20 CPUFreq driver update that will allow to utilize the generic cpufreq-dt driver by moving intermediate clock selection into the clock driver. Note that technically this patch could be squashed into clk-super.c, but it is cleaner to have a separate source file. Also note that currently all CCLKLP bits are left in the clk-super.c and only CCLKG is supported by clk-tegra-super-cclk. It shouldn't be difficult to move the CCLKLP bits, but CCLKLP is not used by anything in kernel and thus better not to touch it for now. Acked-by: Peter De Schrijver Tested-by: Peter Geis Tested-by: Marcel Ziswiler Tested-by: Jasper Korten Tested-by: David Heidelberg Tested-by: Nicolas Chauvet Signed-off-by: Dmitry Osipenko Signed-off-by: Thierry Reding

clk: tegra: Implement Tegra210 EMC clock

2020-05-12T20:48:42Z

The EMC clock needs to carefully coordinate with the EMC controller programming to make sure external memory can be properly clocked. Do so by hooking up the EMC clock with an EMC provider that will specify which rates are supported by the EMC and provide a callback to use for setting the clock rate at the EMC. Based on work by Peter De Schrijver . Signed-off-by: Joseph Lo Signed-off-by: Thierry Reding

clk: tegra: Rename Tegra124 EMC clock source file

2020-05-12T20:48:41Z

This code is only used on Tegra124, so rename it accordingly to make it more consistent with other file names. While at it, also get rid of the TEGRA_CLK_EMC Kconfig symbol that's really just an alias for TEGRA124_EMC. Signed-off-by: Thierry Reding

clk: tegra: Remove tegra_pmc_clk_init along with clk ids

2020-03-12T10:34:04Z

Current Tegra clock driver registers PMC clocks clk_out_1, clk_out_2, clk_out_3 and 32KHz blink output in tegra_pmc_init() which does direct PMC register access during clk_ops and these PMC register read and write access will not happen when PMC is in secure mode. Any direct PMC register access from non-secure world will not go through. All the PMC clocks are moved to Tegra PMC driver with PMC as a clock provider. This patch removes tegra_pmc_clk_init along with corresponding clk ids from Tegra clock driver. Tested-by: Dmitry Osipenko Reviewed-by: Dmitry Osipenko Signed-off-by: Sowjanya Komatineni Signed-off-by: Thierry Reding

clk: tegra: Add suspend and resume support on Tegra210

2019-11-11T13:53:04Z

All the CAR controller settings are lost on suspend when core power goes off. This implement saving and restoring context for all PLLs and clocks during system suspend and resume to have the clocks back to same state for normal operation. Clock driver suspend and resume are registered as syscore_ops as clocks restore need to happen before the other drivers resume to have all their clocks back to the same state as before suspend. Signed-off-by: Sowjanya Komatineni Reviewed-by: Dmitry Osipenko Signed-off-by: Thierry Reding