linux-kernel - [PATCH v5 4/5] clk: spacemit: k1: Add TWSI8 bus and function clocks

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Message-ID: <20250306175750.22480-6-heylenay@4d2.org>
Date: Thu,  6 Mar 2025 17:57:50 +0000
From: Haylen Chu <heylenay@....org>
To: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Haylen Chu <heylenay@...look.com>,
	Yixun Lan <dlan@...too.org>
Cc: linux-riscv@...ts.infradead.org,
	linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	spacemit@...ts.linux.dev,
	Inochi Amaoto <inochiama@...look.com>,
	Chen Wang <unicornxdotw@...mail.com>,
	Jisheng Zhang <jszhang@...nel.org>,
	Meng Zhang <zhangmeng.kevin@...ux.spacemit.com>,
	Haylen Chu <heylenay@....org>
Subject: [PATCH v5 4/5] clk: spacemit: k1: Add TWSI8 bus and function clocks

The control register for TWSI8 clocks, APBC_TWSI8_CLK_RST, contains mux
selection bits, reset assertion bit and enable bits for function and bus
clocks. It has a quirk that reading always results in zero.

As a workaround, let's hardcode the mux value as zero to select
pll1_d78_31p5 as parent and treat twsi8_clk as a gate, whose enable mask
is combined from the real bus and function clocks to avoid the
write-only register being shared between two clk_hws, in which case
updates of one clk_hw zero the other's bits.

With a 1:1 factor serving as placeholder for the bus clock, the I2C-8
controller could be brought up, which is essential for boards attaching
power-management chips to it.

Signed-off-by: Haylen Chu <heylenay@....org>
---
 drivers/clk/spacemit/ccu-k1.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
index 5974a0a1b5f6..44db48ae7131 100644
--- a/drivers/clk/spacemit/ccu-k1.c
+++ b/drivers/clk/spacemit/ccu-k1.c
@@ -558,6 +558,10 @@ static CCU_MUX_GATE_DEFINE(twsi7_clk, twsi_parents,
 			   APBC_TWSI7_CLK_RST,
 			   4, 3, BIT(1),
 			   0);
+static CCU_GATE_DEFINE(twsi8_clk, CCU_PARENT_HW(pll1_d78_31p5),
+		       APBC_TWSI8_CLK_RST,
+		       BIT(1) | BIT(0),
+		       0);
 
 static const struct clk_parent_data timer_parents[] = {
 	CCU_PARENT_HW(pll1_d192_12p8),
@@ -795,6 +799,8 @@ static CCU_GATE_DEFINE(twsi7_bus_clk, CCU_PARENT_HW(apb_clk),
 		       APBC_TWSI7_CLK_RST,
 		       BIT(0),
 		       0);
+static CCU_FACTOR_DEFINE(twsi8_bus_clk, CCU_PARENT_HW(apb_clk),
+			 1, 1);
 
 static CCU_GATE_DEFINE(timers1_bus_clk, CCU_PARENT_HW(apb_clk),
 		       APBC_TIMERS1_CLK_RST,
-- 
2.48.1