Commit Graph

8 Commits

Author SHA1 Message Date
Boris Brezillon 2bf1c98aa5 pwm: rockchip: Add support for atomic update
Implement the ->apply() function to add support for atomic update.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-11 12:49:28 +02:00
Boris Brezillon 48cf973cae pwm: rockchip: Avoid glitches on already running PWMs
The current logic will disable the PWM clk even if the PWM was left
enabled by the bootloader (because it's controlling a critical device
like a regulator for example).
Keep the PWM clk enabled if the PWM is enabled to avoid any glitches.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-11 12:49:27 +02:00
Boris Brezillon 1ebb74cf35 pwm: rockchip: Add support for hardware readout
Implement the ->get_state() function to expose initial state.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-11 12:49:27 +02:00
Boris Brezillon 12f9ce4a51 pwm: rockchip: Fix period and duty cycle approximation
The current implementation always round down the duty and period values,
while it would be better to round them to the closest integer.

These changes are needed in preparation of atomic update support to
prevent a period/duty cycle drift when executing several times the
'pwm_get_state() / modify / pwm_apply_state()' sequence.

Say you have an expected period of 3.333 us and a clk rate of
112.666667 MHz -- the clock frequency doesn't divide evenly, so the
period (stashed in nanoseconds) shrinks when we convert to the register
value and back, as follows:

  pwm_apply_state(): register = period * 112666667 / 1000000000;
  pwm_get_state(): period = register * 1000000000 / 112666667;

or in other words:

  period = period * 112666667 / 1000000000 * 1000000000 / 112666667;

which yields a sequence like:

  3333 -> 3328
  3328 -> 3319
  3319 -> 3310
  3310 -> 3301
  3301 -> 3292
  3292 -> ... (etc) ...

With this patch, we'd see instead:

  period = div_round_closest(period * 112666667, 1000000000) *
                   1000000000 / 112666667;

which yields a stable sequence:

  3333 -> 3337
  3337 -> 3337
  3337 -> ... (etc) ...

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2016-07-11 12:49:26 +02:00
Boris Brezillon 15da7b5001 pwm: Make use of pwm_get_xxx() helpers where appropriate
Use the pwm_get_xxx() helpers instead of directly accessing the fields
in struct pwm_device. This will allow us to smoothly move to the atomic
update approach.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2015-07-20 09:53:22 +02:00
Doug Anderson 7264354c0c pwm: rockchip: Allow polarity invert on rk3288
The rk3288 has the ability to invert the polarity of the PWM.  Let's
enable that ability.  Note that this increases pwm_cells to 3 for
rk3288.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Caesar Wang <caesar.wang@rock-chips.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2014-08-26 10:44:08 +02:00
Caesar Wang f630629908 pwm: rockchip: Added to support for RK3288 SoC
This patch added to support the PWM controller found on
RK3288 SoC.

Signed-off-by: Caesar Wang <caesar.wang@rock-chips.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2014-08-08 13:12:47 +02:00
Beniamino Galvani 101353c82a pwm: add Rockchip SoC PWM support
This commit adds a driver for the PWM controller found on Rockchip
RK29, RK30 and RK31 SoCs.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2014-07-11 15:54:51 +02:00