linux-kernel - [PATCH 0/2] TCB: Add DMA support to read the capture register AB

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Message-ID: <20250528-mchp-tcb-dma-v1-0-083a41fb7b51@microchip.com>
Date: Wed, 28 May 2025 11:43:03 +0530
From: Dharma Balasubiramani <dharma.b@...rochip.com>
To: Kamel Bouhara <kamel.bouhara@...tlin.com>, William Breathitt Gray
	<wbg@...nel.org>, Nicolas Ferre <nicolas.ferre@...rochip.com>, "Alexandre
 Belloni" <alexandre.belloni@...tlin.com>, Claudiu Beznea
	<claudiu.beznea@...on.dev>
CC: <linux-arm-kernel@...ts.infradead.org>, <linux-iio@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Dharma Balasubiramani
	<dharma.b@...rochip.com>
Subject: [PATCH 0/2] TCB: Add DMA support to read the capture register AB

This patch series adds support to enable the DMA support for TCB.

When DMA is used, the Register AB (TC_RAB) address must be configured as
source address of the transfer. TC_RAB provides the next unread value from
TC_RA and TC_RB. It may be read by the DMA after a request has been
triggered upon loading TC_RA or TC_RB.

-----------------------------------
This is tested on sam9x60 curiosity

root@...9x60-curiosity-sd:~# cat /sys/bus/counter/devices/counter0/count0/capture0
258428554
root@...9x60-curiosity-sd:~# devmem2 0xf800800c 
/dev/mem opened.
Memory mapped at address 0xb6f78000.
Read at address  0xF800800C (0xb6f7800c): 0x0F674E8A

Signed-off-by: Dharma Balasubiramani <dharma.b@...rochip.com>
---
Dharma Balasubiramani (2):
      counter: microchip-tcb-capture: Retrieve and map parent base address
      counter: microchip-tcb-capture: Add DMA support for TC_RAB register reads

 drivers/counter/microchip-tcb-capture.c | 128 +++++++++++++++++++++++++++++++-
 include/soc/at91/atmel_tcb.h            |   1 +
 2 files changed, 126 insertions(+), 3 deletions(-)
---
base-commit: fefff2755f2aa4125dce2a1edfe7e545c7c621f2
change-id: 20250528-mchp-tcb-dma-5a29148fe6e6

Best regards,
-- 
Dharma Balasubiramani <dharma.b@...rochip.com>