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Date: Thu, 05 Oct 2017 18:07:52 +1030
From: Andrew Jeffery <andrew@...id.au>
To: Joel Stanley <joel@....id.au>, Lee Jones <lee.jones@...aro.org>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...eaurora.org>
Cc: linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Jeremy Kerr <jk@...abs.org>,
Rick Altherr <raltherr@...gle.com>,
Ryan Chen <ryan_chen@...eedtech.com>,
Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v4 4/5] clk: aspeed: Register gated clocks
On Tue, 2017-10-03 at 17:25 +1030, Joel Stanley wrote:
> The majority of the clocks in the system are gates paired with a reset
> controller that holds the IP in reset.
>
> This borrows from clk_hw_register_gate, but registers two 'gates', one
> to control the clock enable register and the other to control the reset
> IP. This allows us to enforce the ordering:
>
> 1. Place IP in reset
> 2. Enable clock
> 3. Delay
> 4. Release reset
>
> There are some gates that do not have an associated reset; these are
> handled by using -1 as the index for the reset.
>
> Signed-off-by: Joel Stanley <joel@....id.au>
>
> ---
> v4:
> - Drop useless 'disable clock' comment
> - Drop CLK_IS_BASIC flag
> - Fix 'there are a number of clocks...' comment
> - Pass device to clk registration functions
> - Check for errors when registering clk_hws
> v3:
> - Remove gates offset as gates are now at the start of the list
> ---
> drivers/clk/clk-aspeed.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 130 insertions(+)
>
> diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
> index adb295292189..a424b056e767 100644
> --- a/drivers/clk/clk-aspeed.c
> +++ b/drivers/clk/clk-aspeed.c
> @@ -228,6 +228,107 @@ static const struct aspeed_clk_soc_data ast2400_data = {
> .calc_pll = aspeed_ast2400_calc_pll,
> };
>
> +static int aspeed_clk_enable(struct clk_hw *hw)
> +{
> + struct aspeed_clk_gate *gate = to_aspeed_clk_gate(hw);
> + unsigned long flags;
> + u32 clk = BIT(gate->clock_idx);
> + u32 rst = BIT(gate->reset_idx);
> +
> + spin_lock_irqsave(gate->lock, flags);
> +
> + if (gate->reset_idx >= 0) {
> + /* Put IP in reset */
> + regmap_update_bits(gate->map, ASPEED_RESET_CTRL, rst, rst);
> +
> + /* Delay 100us */
> + udelay(100);
> + }
> +
> + /* Enable clock */
> + regmap_update_bits(gate->map, ASPEED_CLK_STOP_CTRL, clk, 0);
> +
> + if (gate->reset_idx >= 0) {
> + /* Delay 10ms */
> + /* TODO: can we sleep here? */
> + msleep(10);
> +
> + /* Take IP out of reset */
> + regmap_update_bits(gate->map, ASPEED_RESET_CTRL, rst, 0);
> + }
> +
> + spin_unlock_irqrestore(gate->lock, flags);
> +
> + return 0;
> +}
> +
> +static void aspeed_clk_disable(struct clk_hw *hw)
> +{
> + struct aspeed_clk_gate *gate = to_aspeed_clk_gate(hw);
> + unsigned long flags;
> + u32 clk = BIT(gate->clock_idx);
> +
> + spin_lock_irqsave(gate->lock, flags);
> +
> + regmap_update_bits(gate->map, ASPEED_CLK_STOP_CTRL, clk, clk);
> +
> + 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 reg;
> +
> + regmap_read(gate->map, ASPEED_CLK_STOP_CTRL, ®);
> +
> + return (reg & clk) ? 0 : 1;
Kill a branch, save the internet: return !(reg & clk);
But regardless, the patch seems sensible to me modulo the power domain
discussion. However as it's more clk-y than Aspeed-y I don't feel entirely
qualified to provide a r-b, so instead:
Acked-by: Andrew Jeffery <andrew@...id.au>
> +}
> +
> +static const struct clk_ops aspeed_clk_gate_ops = {
> + .enable = aspeed_clk_enable,
> + .disable = aspeed_clk_disable,
> + .is_enabled = aspeed_clk_is_enabled,
> +};
> +
> +static struct clk_hw *aspeed_clk_hw_register_gate(struct device *dev,
> + const char *name, const char *parent_name, unsigned long flags,
> + struct regmap *map, u8 clock_idx, u8 reset_idx,
> + u8 clk_gate_flags, spinlock_t *lock)
> +{
> + struct aspeed_clk_gate *gate;
> + struct clk_init_data init;
> + struct clk_hw *hw;
> + int ret;
> +
> + gate = kzalloc(sizeof(*gate), GFP_KERNEL);
> + if (!gate)
> + return ERR_PTR(-ENOMEM);
> +
> + init.name = name;
> + init.ops = &aspeed_clk_gate_ops;
> + init.flags = flags;
> + init.parent_names = parent_name ? &parent_name : NULL;
> + init.num_parents = parent_name ? 1 : 0;
> +
> + gate->map = map;
> + gate->clock_idx = clock_idx;
> + gate->reset_idx = reset_idx;
> + gate->flags = clk_gate_flags;
> + gate->lock = lock;
> + gate->hw.init = &init;
> +
> + hw = &gate->hw;
> + ret = clk_hw_register(dev, hw);
> + if (ret) {
> + kfree(gate);
> + hw = ERR_PTR(ret);
> + }
> +
> + return hw;
> +}
> +
> static int aspeed_clk_probe(struct platform_device *pdev)
> {
> const struct aspeed_clk_soc_data *soc_data;
> @@ -235,6 +336,7 @@ static int aspeed_clk_probe(struct platform_device *pdev)
> struct regmap *map;
> struct clk_hw *hw;
> u32 val, rate;
> + int i;
>
> map = syscon_node_to_regmap(dev->of_node);
> if (IS_ERR(map)) {
> @@ -323,6 +425,34 @@ static int aspeed_clk_probe(struct platform_device *pdev)
> return PTR_ERR(hw);
> aspeed_clk_data->hws[ASPEED_CLK_BCLK] = hw;
>
> + /*
> + * TODO: There are a number of clocks that not included in this driver
> + * as more information is required:
> + * D2-PLL
> + * D-PLL
> + * YCLK
> + * RGMII
> + * RMII
> + * UART[1..5] clock source mux
> + */
> +
> + for (i = 0; i < ARRAY_SIZE(aspeed_gates); i++) {
> + const struct aspeed_gate_data *gd = &aspeed_gates[i];
> +
> + hw = aspeed_clk_hw_register_gate(dev,
> + gd->name,
> + gd->parent_name,
> + gd->flags,
> + map,
> + gd->clock_idx,
> + gd->reset_idx,
> + CLK_GATE_SET_TO_DISABLE,
> + &aspeed_clk_lock);
> + if (IS_ERR(hw))
> + return PTR_ERR(hw);
> + aspeed_clk_data->hws[i] = hw;
> + }
> +
> return 0;
> };
>
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