From d9a6a7cbffe25c366754e6b1260372bae08037e9 Mon Sep 17 00:00:00 2001 From: Eddie James Date: Thu, 8 Mar 2018 14:57:20 -0600 Subject: [PATCH] clk: aspeed: Prevent reset if clock is enabled According to the Aspeed specification, the reset and enable sequence should be done when the clock is stopped. The specification doesn't define behavior if the reset is done while the clock is enabled. From testing on the AST2500, the LPC Controller has problems if the clock is reset while enabled. Therefore, check whether the clock is enabled or not before performing the reset and enable sequence in the Aspeed clock driver. Reported-by: Lei Yu Signed-off-by: Eddie James Fixes: 5356c904a8aa ("clk: aspeed: Register gated clocks") Reviewed-by: Joel Stanley Signed-off-by: Stephen Boyd --- drivers/clk/clk-aspeed.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c index 168777175cd1e..5eb50c31e4553 100644 --- a/drivers/clk/clk-aspeed.c +++ b/drivers/clk/clk-aspeed.c @@ -205,6 +205,18 @@ static const struct aspeed_clk_soc_data ast2400_data = { .calc_pll = aspeed_ast2400_calc_pll, }; +static int aspeed_clk_is_enabled(struct clk_hw *hw) +{ + struct aspeed_clk_gate *gate = to_aspeed_clk_gate(hw); + u32 clk = BIT(gate->clock_idx); + u32 enval = (gate->flags & CLK_GATE_SET_TO_DISABLE) ? 0 : clk; + u32 reg; + + regmap_read(gate->map, ASPEED_CLK_STOP_CTRL, ®); + + return ((reg & clk) == enval) ? 1 : 0; +} + static int aspeed_clk_enable(struct clk_hw *hw) { struct aspeed_clk_gate *gate = to_aspeed_clk_gate(hw); @@ -215,6 +227,11 @@ static int aspeed_clk_enable(struct clk_hw *hw) spin_lock_irqsave(gate->lock, flags); + if (aspeed_clk_is_enabled(hw)) { + spin_unlock_irqrestore(gate->lock, flags); + return 0; + } + if (gate->reset_idx >= 0) { /* Put IP in reset */ regmap_update_bits(gate->map, ASPEED_RESET_CTRL, rst, rst); @@ -255,18 +272,6 @@ static void aspeed_clk_disable(struct clk_hw *hw) spin_unlock_irqrestore(gate->lock, flags); } -static int aspeed_clk_is_enabled(struct clk_hw *hw) -{ - struct aspeed_clk_gate *gate = to_aspeed_clk_gate(hw); - u32 clk = BIT(gate->clock_idx); - u32 enval = (gate->flags & CLK_GATE_SET_TO_DISABLE) ? 0 : clk; - u32 reg; - - regmap_read(gate->map, ASPEED_CLK_STOP_CTRL, ®); - - return ((reg & clk) == enval) ? 1 : 0; -} - static const struct clk_ops aspeed_clk_gate_ops = { .enable = aspeed_clk_enable, .disable = aspeed_clk_disable, -- 2.39.5