Re: [PATCH v3] clk/axs10x: Add I2S PLL clock driver

[Stephen Boyd <sboyd@codeaurora.org>]

On 03/31, Jose Abreu wrote:
>
>  arch/arc/boot/dts/axs10x_mb.dtsi   |   5 ++

Please remove this diff from this patch. dts changes go through
non-clk trees.

>  drivers/clk/Makefile               |   1 +
>  drivers/clk/axs10x/Makefile        |   1 +
>  drivers/clk/axs10x/i2s_pll_clock.c | 163 +++++++++++++++++++++++++++++++++++++

Where is the binding document?

> diff --git a/drivers/clk/axs10x/i2s_pll_clock.c b/drivers/clk/axs10x/i2s_pll_clock.c
> new file mode 100644
> index 0000000..f050e70
> --- /dev/null
> +++ b/drivers/clk/axs10x/i2s_pll_clock.c
> @@ -0,0 +1,163 @@
> +/* FPGA Version Info */
> +#define FPGA_VER_INFO	0xE0011230
> +#define FPGA_VER_27M	0x000FBED9
> +
> +/* PLL registers addresses */
> +#define PLL_IDIV_ADDR	0xE00100A0
> +#define PLL_FBDIV_ADDR	0xE00100A4
> +#define PLL_ODIV0_ADDR	0xE00100A8
> +#define PLL_ODIV1_ADDR	0xE00100AC
> +
> +struct i2s_pll_cfg {
> +	unsigned int rate;
> +	unsigned int idiv;
> +	unsigned int fbdiv;
> +	unsigned int odiv0;
> +	unsigned int odiv1;
> +};
> +
> +static struct i2s_pll_cfg i2s_pll_cfg_27m[] = {

const?

> +	/* 27 Mhz */
> +	{ 1024000, 0x104, 0x451, 0x10E38, 0x2000 },
> +	{ 1411200, 0x104, 0x596, 0x10D35, 0x2000 },
> +	{ 1536000, 0x208, 0xA28, 0x10B2C, 0x2000 },
> +	{ 2048000, 0x82, 0x451, 0x10E38, 0x2000 },
> +	{ 2822400, 0x82, 0x596, 0x10D35, 0x2000 },
> +	{ 3072000, 0x104, 0xA28, 0x10B2C, 0x2000 },
> +	{ 2116800, 0x82, 0x3CF, 0x10C30, 0x2000 },
> +	{ 2304000, 0x104, 0x79E, 0x10B2C, 0x2000 },
> +	{ 0, 0, 0, 0, 0 },
> +};
> +
> +static struct i2s_pll_cfg i2s_pll_cfg_28m[] = {

const?

> +	/* 28.224 Mhz */
> +	{ 1024000, 0x82, 0x105, 0x107DF, 0x2000 },
> +	{ 1411200, 0x28A, 0x1, 0x10001, 0x2000 },
> +	{ 1536000, 0xA28, 0x187, 0x10042, 0x2000 },
> +	{ 2048000, 0x41, 0x105, 0x107DF, 0x2000 },
> +	{ 2822400, 0x145, 0x1, 0x10001, 0x2000 },
> +	{ 3072000, 0x514, 0x187, 0x10042, 0x2000 },
> +	{ 2116800, 0x514, 0x42, 0x10001, 0x2000 },
> +	{ 2304000, 0x619, 0x82, 0x10001, 0x2000 },
> +	{ 0, 0, 0, 0, 0 },
> +};
> +
> +struct i2s_pll_clk {
> +	struct clk_hw hw;
> +	unsigned long ref_clk;
> +	struct i2s_pll_cfg *pll_cfg;
> +};
> +
> +static inline struct i2s_pll_clk *to_i2s_pll_clk(struct clk_hw *hw)
> +{
> +	return container_of(hw, struct i2s_pll_clk, hw);
> +}
> +
> +static unsigned int i2s_pll_get_value(unsigned int val)
> +{
> +	return ((val & 0x3F) + ((val >> 6) & 0x3F));

Please drop extraneous parentheses.

> +}
> +
> +static unsigned long i2s_pll_recalc_rate(struct clk_hw *hw,
> +			unsigned long parent_rate)
> +{
> +	struct i2s_pll_clk *clk = to_i2s_pll_clk(hw);
> +	unsigned int idiv, fbdiv, odiv;
> +
> +	idiv = i2s_pll_get_value(readl((void *)PLL_IDIV_ADDR));

We need a real ioremap in this driver instead of casting physical
addresses to pointers and calling readl on them.

> +	fbdiv = i2s_pll_get_value(readl((void *)PLL_FBDIV_ADDR));
> +	odiv = i2s_pll_get_value(readl((void *)PLL_ODIV0_ADDR));
> +
> +	return (((clk->ref_clk / idiv ) * fbdiv) / odiv);

Again, too many parentheses. Also, any concerns of 32-bit
truncation here (i.e. is 64-bit math needed)?

> +}
> +
> +static long i2s_pll_round_rate(struct clk_hw *hw, unsigned long rate,
> +			unsigned long *prate)
> +{
> +	/* TODO: Round rate to nearest valid rate */

At the least this should return the rate from the table if it's
there or failure if it isn't an exact match. Basically do exactly
what i2s_pll_set_rate() is doing without changing the rate.

> +	return rate;
> +}
> +
> +static int i2s_pll_set_rate(struct clk_hw *hw, unsigned long rate,
> +			unsigned long parent_rate)
> +{
> +	struct i2s_pll_cfg *pll_cfg = to_i2s_pll_clk(hw)->pll_cfg;
> +	int i;
> +
> +	for (i = 0; pll_cfg[i].rate != 0; i++) {
> +		if (pll_cfg[i].rate == rate) {
> +			writel(pll_cfg[i].idiv, (void *)PLL_IDIV_ADDR);
> +			writel(pll_cfg[i].fbdiv, (void *)PLL_FBDIV_ADDR);
> +			writel(pll_cfg[i].odiv0, (void *)PLL_ODIV0_ADDR);
> +			writel(pll_cfg[i].odiv1, (void *)PLL_ODIV1_ADDR);
> +			return 0;
> +		}
> +	}
> +
> +	pr_err("%s: invalid rate=%ld, parent_rate=%ld\n", __func__,
> +			rate, parent_rate);
> +	return -EINVAL;
> +}
> +
> +static const struct clk_ops i2s_pll_ops = {
> +	.recalc_rate = i2s_pll_recalc_rate,
> +	.round_rate = i2s_pll_round_rate,
> +	.set_rate = i2s_pll_set_rate,
> +};
> +
> +static void __init i2s_pll_clk_setup(struct device_node *node)
> +{
> +	const char *clk_name = node->name;
> +	struct clk *clk;
> +	struct i2s_pll_clk *pll_clk;
> +	struct clk_init_data init;
> +
> +	pll_clk = kzalloc(sizeof(*pll_clk), GFP_KERNEL);
> +	if (!pll_clk)
> +		return;
> +
> +	init.name = clk_name;
> +	init.ops = &i2s_pll_ops;
> +	init.flags = CLK_IS_BASIC;

Drop CLK_IS_BASIC unless you actually need it.

> +	init.num_parents = 0;
> +	pll_clk->hw.init = &init;
> +
> +	clk = clk_register(NULL, &pll_clk->hw);
> +	if (IS_ERR(clk)) {
> +		pr_err("%s: failed to register %s div clock (%ld)\n",
> +				__func__, clk_name, PTR_ERR(clk));
> +		goto free_clock;
> +	}
> +
> +	if (readl((void *)FPGA_VER_INFO) <= FPGA_VER_27M) {
> +		pll_clk->ref_clk = 27000000;

Refclk sounds like parent clk. Perhaps the DTS file should have a
fixes rate reference clk for this clk and then we could use
parent/child relationships in the clk framework to pass the
parent rate to the recalc/round_rate ops? I presume that the FPGA
info isn't in the same device/region as this clk is.

> +		pll_clk->pll_cfg = i2s_pll_cfg_27m;
> +	} else {
> +		pll_clk->ref_clk = 28224000;
> +		pll_clk->pll_cfg = i2s_pll_cfg_28m;
> +	}
> +
> +	of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +	return;
> +
> +free_clock:
> +	kfree(pll_clk);
> +}
> +
> +CLK_OF_DECLARE(i2s_pll_clk, "snps,i2s-pll-clock", i2s_pll_clk_setup);
> +

Can this be a platform driver instead of using CLK_OF_DECLARE?

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