Re: [PATCH v2 2/5] soc: samsung: Add USI driver
From: Krzysztof Kozlowski <hidden>
Date: 2021-11-30 08:25:16
Also in:
linux-devicetree, linux-samsung-soc, linux-serial, lkml
On 30/11/2021 03:31, Sam Protsenko wrote:
On Tue, 30 Nov 2021 at 04:24, Sam Protsenko [off-list ref] wrote:quoted
USIv2 IP-core is found on modern ARM64 Exynos SoCs (like Exynos850) and provides selectable serial protocol (one of: UART, SPI, I2C). USIv2 registers usually reside in the same register map as a particular underlying protocol it implements, but have some particular offset. E.g. on Exynos850 the USI_UART has 0x13820000 base address, where UART registers have 0x00..0x40 offsets, and USI registers have 0xc0..0xdc offsets. Desired protocol can be chosen via SW_CONF register from System Register block of the same domain as USI. Before starting to use a particular protocol, USIv2 must be configured properly: 1. Select protocol to be used via System Register 2. Clear "reset" flag in USI_CON 3. Configure HWACG behavior (e.g. for UART Rx the HWACG must be disabled, so that the IP clock is not gated automatically); this is done using USI_OPTION register 4. Keep both USI clocks (PCLK and IPCLK) running during USI registers modification This driver implements above behavior. Of course, USIv2 driver should be probed before UART/I2C/SPI drivers. It can be achived by embedding UART/I2C/SPI nodes inside of USI node (in Device Tree); driver then walks underlying nodes and instantiates those. Driver also handles USI configuration on PM resume, as register contents can be lost during CPU suspend. This driver is designed with different USI versions in mind. So it should be relatively easy to add new USI revisions to it later. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> ---I'm sorry for sending this v2 series as a bunch of separate mails. My msmtp failed in the middle of submission, two times in a row. If it's a bother, please tell me and I'll re-send as v3.
You can always fix it by using --in-reply-to and --no-thread. This unfortunately breaks b4, so please resend (can be v2 RESEND): Looking up https://lore.kernel.org/r/20211130022250.28519-1-semen.protsenko%40linaro.org Grabbing thread from lore.kernel.org/all/20211130022250.28519-1-semen.protsenko%40linaro.org/t.mbox.gz Analyzing 2 messages in the thread Checking attestation on all messages, may take a moment... ✓ [PATCH v2 1/5] dt-bindings: soc: samsung: Add Exynos USI bindings ✓ Signed: DKIM/linaro.org ERROR: missing [2/5]! ERROR: missing [3/5]! ERROR: missing [4/5]! ERROR: missing [5/5]! Best regards, Krzysztof _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel