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Subject[PATCH v2 4/5] clk: aspeed: Register gated clocks
Date
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@jms.id.au>
---
drivers/clk/clk-aspeed.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 128 insertions(+)

diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
index 19531798e040..dec9db4ec47b 100644
--- a/drivers/clk/clk-aspeed.c
+++ b/drivers/clk/clk-aspeed.c
@@ -191,6 +191,108 @@ static struct clk_hw *aspeed_calc_pll(const char *name, u32 val)
mult, div);
}

+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);
+
+ /* Disable clock */
+ 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, &reg);
+
+ return (reg & clk) ? 0 : 1;
+}
+
+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 | CLK_IS_BASIC;
+ 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 __init aspeed_clk_probe(struct platform_device *pdev)
{
const struct aspeed_clk_soc_data *soc_data;
@@ -200,6 +302,7 @@ static int __init 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)) {
@@ -269,6 +372,31 @@ static int __init aspeed_clk_probe(struct platform_device *pdev)
&aspeed_clk_lock);
aspeed_clk_data->hws[ASPEED_CLK_BCLK] = hw;

+ /* 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;
+
+ gd = &aspeed_gates[i];
+ aspeed_clk_data->hws[ASPEED_CLK_GATES + i] =
+ aspeed_clk_hw_register_gate(NULL, gd->name,
+ gd->parent_name,
+ gd->flags,
+ map,
+ gd->clock_idx,
+ gd->reset_idx,
+ CLK_GATE_SET_TO_DISABLE,
+ &aspeed_clk_lock);
+ }
+
return 0;
};

--
2.14.1
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