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Message-Id: <20200102080929.0EE2C215A4@mail.kernel.org>
Date: Thu, 02 Jan 2020 00:09:28 -0800
From: Stephen Boyd <sboyd@...nel.org>
To: Michael Walle <michael@...le.cc>
Cc: devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
linux-kernel@...r.kernel.org,
Michael Turquette <mturquette@...libre.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 2/2] clk: fsl-sai: new driver
Quoting Michael Walle (2020-01-01 07:15:32)
>
> Hi Stephen,
>
> thanks for the review.
>
> Am 2019-12-24 09:05, schrieb Stephen Boyd:
> > Quoting Michael Walle (2019-12-09 15:33:05)
> >> diff --git a/drivers/clk/clk-fsl-sai.c b/drivers/clk/clk-fsl-sai.c
> >> new file mode 100644
> >> index 000000000000..b92054d15ab1
> >> --- /dev/null
> >> +++ b/drivers/clk/clk-fsl-sai.c
> >> @@ -0,0 +1,84 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Freescale SAI BCLK as a generic clock driver
> >> + *
> >> + * Copyright 2019 Kontron Europe GmbH
> >> + */
> >> +
> >> +#include <linux/clk-provider.h>
> >> +#include <linux/err.h>
> >> +#include <linux/of.h>
> >> +#include <linux/of_address.h>
> >> +#include <linux/slab.h>
> >> +
> >> +#define I2S_CSR 0x00
> >> +#define I2S_CR2 0x08
> >> +#define CSR_BCE_BIT 28
> >> +#define CR2_BCD BIT(24)
> >> +#define CR2_DIV_SHIFT 0
> >> +#define CR2_DIV_WIDTH 8
> >> +
> >> +struct fsl_sai_clk {
> >> + struct clk_divider div;
> >> + struct clk_gate gate;
> >> + spinlock_t lock;
> >> +};
> >> +
> >> +static void __init fsl_sai_clk_setup(struct device_node *node)
> >> +{
> >> + const char *clk_name = node->name;
> >> + struct fsl_sai_clk *sai_clk;
> >> + unsigned int num_parents;
> >> + const char *parent_name;
> >> + void __iomem *base;
> >> + struct clk_hw *hw;
> >> +
> >> + num_parents = of_clk_get_parent_count(node);
> >> + if (!num_parents) {
> >> + pr_err("%s: no parent found", clk_name);
> >> + return;
> >> + }
> >> +
> >> + parent_name = of_clk_get_parent_name(node, 0);
> >
> > Could this use the new way of specifying clk parents so that we don't
> > have to query DT for parent names and just let the core framework do it
> > whenever it needs to?
>
> you mean specifying parent_data with .index = 0? Seems like
> clk_composite
> does not support this. The parent can only be specified by supplying the
> clock names.
>
> I could add that in a separate patch. What do you think about the
> following new functions, where a driver can use parent_data instead
> of parent_names.
I started doing this in
https://lkml.kernel.org/r/20190830150923.259497-1-sboyd@kernel.org but I
never got around to the composite clks. Sounds fine to add this new API
for your use case.
>
> +struct clk *clk_register_composite_pdata(struct device *dev, const char
> *name,
> + const struct clk_parent_data *parent_data,
> + struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
> + struct clk_hw *rate_hw, const struct clk_ops *rate_ops,
> + struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
> + unsigned long flags);
>
> +struct clk_hw *clk_hw_register_composite_pdata(struct device *dev,
> + const char *name, const struct clk_parent_data
> *parent_data,
> + struct clk_hw *mux_hw, const struct clk_ops *mux_ops,
> + struct clk_hw *rate_hw, const struct clk_ops *rate_ops,
> + struct clk_hw *gate_hw, const struct clk_ops *gate_ops,
> + unsigned long flags);
>
>
> >> +
> >> + sai_clk = kzalloc(sizeof(*sai_clk), GFP_KERNEL);
> >> + if (!sai_clk)
> >> + return;
> >> +
> >> + base = of_iomap(node, 0);
> >> + if (base == NULL) {
> >> + pr_err("%s: failed to map register space", clk_name);
> >> + goto err;
> >> + }
> >> +
> >> + spin_lock_init(&sai_clk->lock);
> >> +
> >> + sai_clk->gate.reg = base + I2S_CSR;
> >> + sai_clk->gate.bit_idx = CSR_BCE_BIT;
> >> + sai_clk->gate.lock = &sai_clk->lock;
> >> +
> >> + sai_clk->div.reg = base + I2S_CR2;
> >> + sai_clk->div.shift = CR2_DIV_SHIFT;
> >> + sai_clk->div.width = CR2_DIV_WIDTH;
> >> + sai_clk->div.lock = &sai_clk->lock;
> >> +
> >> + /* set clock direction, we are the BCLK master */
> >
> > Should this configuration come from DT somehow?
>
> No, we are always master, because as a slave, there would be no clock
> output ;)
Got it.
>
> >> + writel(CR2_BCD, base + I2S_CR2);
> >> +
> >> + hw = clk_hw_register_composite(NULL, clk_name, &parent_name,
> >> 1,
> >> + NULL, NULL,
> >> + &sai_clk->div.hw,
> >> &clk_divider_ops,
> >> + &sai_clk->gate.hw,
> >> &clk_gate_ops,
> >> + CLK_SET_RATE_GATE);
> >> + if (IS_ERR(hw))
> >> + goto err;
> >> +
> >> + of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
> >> +
> >> + return;
> >> +
> >> +err:
> >> + kfree(sai_clk);
> >> +}
> >> +
> >> +CLK_OF_DECLARE(fsl_sai_clk, "fsl,vf610-sai-clock",
> >> fsl_sai_clk_setup);
> >
> > Is there a reason this can't be a platform device driver?
>
> I don't think so, the user will be a sound codec for now. I'll convert
> it
> to a platform device, in that case I could also use the devm_ variants.
>
Awesome. Thanks!
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