clk: aspeed: Register gated clocks

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.

Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 130 insertions, 0 deletions

diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
index cf5ea63feb31..dbd3c7774831 100644
--- a/drivers/clk/clk-aspeed.c
+++ b/drivers/clk/clk-aspeed.c
@@ -204,6 +204,106 @@ 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) {
+                /* A delay of 10ms is specified by the ASPEED docs */
+                mdelay(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, &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;
+        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;
@@ -211,6 +311,7 @@ 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)) {
@@ -283,6 +384,35 @@ 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
+         *   Video Engine (ECLK) mux and clock divider
+         */
+
+        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;
 };