From 8a53fc511c5ec81347b981b438f68c3dde421608 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: 15ed8ce5f84e ("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 1687771..5eb50c3 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, -- 2.7.4