Re: [PATCH v2 6/6] clk: mvebu: Add the peripheral clock driver for Armada 3700

[Michael Turquette]

Quoting Gregory CLEMENT (2016-07-07 15:37:51)
> +#include <linux/clk-provider.h>
> +#include <linux/clk.h>

Same question as my previous email. Is clk.h necessary? Is this driver
also a clk consumer?

> +static int armada_3700_add_composite_clk(const struct clk_periph_data *data,
> +                                        const char * const *parent_name,
> +                                        void __iomem *reg, spinlock_t *lock,
> +                                        struct device *dev, struct clk_hw *hw)
> +{
> +       const struct clk_ops *mux_ops = NULL, *gate_ops = NULL,
> +               *div_ops = NULL;
> +       struct clk_hw *mux_hw = NULL, *gate_hw = NULL, *div_hw = NULL;
> +       const char * const *names;
> +       struct clk_mux *mux = NULL;
> +       struct clk_gate *gate = NULL;
> +       struct clk_divider *div = NULL;
> +       struct clk_double_div *double_div = NULL;
> +       int num_parent;
> +       int ret = 0;
> +
> +       if (data->gate_shift != UNUSED) {
> +               gate = devm_kzalloc(dev, sizeof(*gate), GFP_KERNEL);
> +
> +               if (!gate)
> +                       return -ENOMEM;
> +
> +               gate->reg = reg + CLK_DIS;
> +               gate->bit_idx = data->gate_shift;
> +               gate->lock = lock;
> +               gate_ops = &clk_gate_ops;
> +               gate_hw = &gate->hw;
> +       }
> +
> +       if (data->mux_shift != UNUSED) {
> +               mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
> +
> +               if (!mux) {
> +                       ret = -ENOMEM;
> +                       goto free_gate;
> +               }
> +
> +               mux->reg = reg + TBG_SEL;
> +               mux->shift = data->mux_shift;
> +               mux->mask = 0x3;
> +               mux->lock = lock;
> +               mux_ops = &clk_mux_ro_ops;
> +               mux_hw = &mux->hw;
> +       }
> +
> +       if (data->div_reg1 != UNUSED) {
> +               if (data->div_reg2 == UNUSED) {
> +                       const struct clk_div_table *clkt;
> +                       int table_size = 0;
> +
> +                       div = devm_kzalloc(dev, sizeof(*div), GFP_KERNEL);
> +                       if (!div) {
> +                               ret = -ENOMEM;
> +                               goto free_mux;
> +                       }
> +
> +                       div->reg = reg + data->div_reg1;
> +                       div->table = data->table;
> +                       for (clkt = div->table; clkt->div; clkt++)
> +                               table_size++;
> +                       div->width = order_base_2(table_size);
> +                       div->lock = lock;
> +                       div_ops = &clk_divider_ro_ops;
> +                       div_hw = &div->hw;
> +               } else {
> +                       double_div = devm_kzalloc(dev, sizeof(*double_div),
> +                                                 GFP_KERNEL);
> +                       if (!double_div) {
> +                               ret = -ENOMEM;
> +                               goto free_mux;
> +                       }
> +
> +                       double_div->reg1 = reg + data->div_reg1;
> +                       double_div->shift1 = data->div_shift1;
> +                       double_div->reg2 = reg + data->div_reg1;
> +                       double_div->shift2 = data->div_shift2;
> +                       div_ops = &clk_double_div_ops;
> +                       div_hw = &double_div->hw;
> +               }
> +       }
> +
> +       switch (data->flags) {
> +       case XTAL_CHILD:
> +               /* the xtal clock is the 5th clock */
> +               names = &parent_name[4];
> +               num_parent = 1;
> +               break;
> +       case TBGA_S_CHILD:
> +               /* the TBG A S clock is the 3rd clock */
> +               names = &parent_name[2];
> +               num_parent = 1;
> +               break;
> +       case GBE_CORE_CHILD:
> +               names = &gbe_name[1];
> +               num_parent = 1;
> +               break;
> +       case  GBE_50_CHILD:
> +               names = &gbe_name[0];
> +               num_parent = 1;
> +               break;
> +       case  GBE_125_CHILD:
> +               names = &gbe_name[2];
> +               num_parent = 1;
> +               break;
> +       default:
> +               names = parent_name;
> +               num_parent = 4;
> +       }
> +       hw = clk_hw_register_composite(dev, data->name,
> +                                    names, num_parent,
> +                                    mux_hw, mux_ops,
> +                                    div_hw, div_ops,
> +                                    gate_hw, gate_ops,
> +                                    CLK_IGNORE_UNUSED);
> +       if (IS_ERR(hw)) {
> +               ret = PTR_ERR(hw);
> +               goto free_div;
> +       }
> +
> +       return 0;
> +free_div:
> +       devm_kfree(dev, div);
> +       devm_kfree(dev, double_div);
> +free_mux:
> +       devm_kfree(dev, mux);
> +free_gate:
> +       devm_kfree(dev, gate);
> +       return ret;
> +}

Can this "add" function (aka registration function) be replaced with
static data instead? I think that all of the static data exists already,
this function can be removed and your probe can call clk_hw_register
directly.

It might need a macro though, since composite clock structures are
rather messy. This avoids a lot of unnecessary allocations and time
populating data that we already have access to. In general I am trying
to encourage clk drivers to use only clk_hw_register() in their probe
instead of the helper registration functions.

Similarly I am discouraging drivers from populating hw.init at run-time,
since we already have that data for that at compile-time.

Regards,
Mike