From 97689a1a3fdad101d41488f9da0b1d99aa0b6aa2 Mon Sep 17 00:00:00 2001 From: Paul Cercueil Date: Wed, 24 Jul 2019 13:16:04 -0400 Subject: doc: Add doc for the Ingenic TCU hardware Add documentation about the Timer/Counter Unit (TCU) present in the Ingenic JZ47xx SoCs. The Timer/Counter Unit (TCU) in Ingenic JZ47xx SoCs is a multi-function hardware block. It features up to to eight channels, that can be used as counters, timers, or PWM. - JZ4725B, JZ4750, JZ4755 only have six TCU channels. The other SoCs all have eight channels. - JZ4725B introduced a separate channel, called Operating System Timer (OST). It is a 32-bit programmable timer. On JZ4770 and above, it is 64-bit. - Each one of the TCU channels has its own clock, which can be reparented to three different clocks (pclk, ext, rtc), gated, and reclocked, through their TCSR register. * The watchdog and OST hardware blocks also feature a TCSR register with the same format in their register space. * The TCU registers used to gate/ungate can also gate/ungate the watchdog and OST clocks. - Each TCU channel works in one of two modes: * mode TCU1: channels cannot work in sleep mode, but are easier to operate. * mode TCU2: channels can work in sleep mode, but the operation is a bit more complicated than with TCU1 channels. - The mode of each TCU channel depends on the SoC used: * On the oldest SoCs (up to JZ4740), all of the eight channels operate in TCU1 mode. * On JZ4725B, channel 5 operates as TCU2, the others operate as TCU1. * On newest SoCs (JZ4750 and above), channels 1-2 operate as TCU2, the others operate as TCU1. - Each channel can generate an interrupt. Some channels share an interrupt line, some don't, and this changes between SoC versions: * on older SoCs (JZ4740 and below), channel 0 and channel 1 have their own interrupt line; channels 2-7 share the last interrupt line. * On JZ4725B, channel 0 has its own interrupt; channels 1-5 share one interrupt line; the OST uses the last interrupt line. * on newer SoCs (JZ4750 and above), channel 5 has its own interrupt; channels 0-4 and (if eight channels) 6-7 all share one interrupt line; the OST uses the last interrupt line. Signed-off-by: Paul Cercueil Tested-by: Mathieu Malaterre Tested-by: Artur Rojek Signed-off-by: Paul Burton Cc: Ralf Baechle Cc: James Hogan Cc: Jonathan Corbet Cc: Lee Jones Cc: Arnd Bergmann Cc: Daniel Lezcano Cc: Thomas Gleixner Cc: Michael Turquette Cc: Stephen Boyd Cc: Jason Cooper Cc: Marc Zyngier Cc: Rob Herring Cc: Mark Rutland Cc: devicetree@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-mips@vger.kernel.org Cc: linux-clk@vger.kernel.org Cc: od@zcrc.me --- Documentation/mips/index.rst | 11 ++++++ Documentation/mips/ingenic-tcu.rst | 71 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 82 insertions(+) create mode 100644 Documentation/mips/index.rst create mode 100644 Documentation/mips/ingenic-tcu.rst (limited to 'Documentation/mips') diff --git a/Documentation/mips/index.rst b/Documentation/mips/index.rst new file mode 100644 index 000000000000..321b4794f3b8 --- /dev/null +++ b/Documentation/mips/index.rst @@ -0,0 +1,11 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================== +MIPS-specific Documentation +=========================== + +.. toctree:: + :maxdepth: 1 + :numbered: + + ingenic-tcu diff --git a/Documentation/mips/ingenic-tcu.rst b/Documentation/mips/ingenic-tcu.rst new file mode 100644 index 000000000000..c4ef4c45aade --- /dev/null +++ b/Documentation/mips/ingenic-tcu.rst @@ -0,0 +1,71 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================================== +Ingenic JZ47xx SoCs Timer/Counter Unit hardware +=============================================== + +The Timer/Counter Unit (TCU) in Ingenic JZ47xx SoCs is a multi-function +hardware block. It features up to to eight channels, that can be used as +counters, timers, or PWM. + +- JZ4725B, JZ4750, JZ4755 only have six TCU channels. The other SoCs all + have eight channels. + +- JZ4725B introduced a separate channel, called Operating System Timer + (OST). It is a 32-bit programmable timer. On JZ4760B and above, it is + 64-bit. + +- Each one of the TCU channels has its own clock, which can be reparented to three + different clocks (pclk, ext, rtc), gated, and reclocked, through their TCSR register. + + - The watchdog and OST hardware blocks also feature a TCSR register with the same + format in their register space. + - The TCU registers used to gate/ungate can also gate/ungate the watchdog and + OST clocks. + +- Each TCU channel works in one of two modes: + + - mode TCU1: channels cannot work in sleep mode, but are easier to + operate. + - mode TCU2: channels can work in sleep mode, but the operation is a bit + more complicated than with TCU1 channels. + +- The mode of each TCU channel depends on the SoC used: + + - On the oldest SoCs (up to JZ4740), all of the eight channels operate in + TCU1 mode. + - On JZ4725B, channel 5 operates as TCU2, the others operate as TCU1. + - On newest SoCs (JZ4750 and above), channels 1-2 operate as TCU2, the + others operate as TCU1. + +- Each channel can generate an interrupt. Some channels share an interrupt + line, some don't, and this changes between SoC versions: + + - on older SoCs (JZ4740 and below), channel 0 and channel 1 have their + own interrupt line; channels 2-7 share the last interrupt line. + - On JZ4725B, channel 0 has its own interrupt; channels 1-5 share one + interrupt line; the OST uses the last interrupt line. + - on newer SoCs (JZ4750 and above), channel 5 has its own interrupt; + channels 0-4 and (if eight channels) 6-7 all share one interrupt line; + the OST uses the last interrupt line. + +Implementation +============== + +The functionalities of the TCU hardware are spread across multiple drivers: + +=========== ===== +clocks drivers/clk/ingenic/tcu.c +interrupts drivers/irqchip/irq-ingenic-tcu.c +timers drivers/clocksource/ingenic-timer.c +OST drivers/clocksource/ingenic-ost.c +PWM drivers/pwm/pwm-jz4740.c +watchdog drivers/watchdog/jz4740_wdt.c +=========== ===== + +Because various functionalities of the TCU that belong to different drivers +and frameworks can be controlled from the same registers, all of these +drivers access their registers through the same regmap. + +For more information regarding the devicetree bindings of the TCU drivers, +have a look at Documentation/devicetree/bindings/mfd/ingenic,tcu.txt. -- cgit