[PATCH 2/3] clk: hisilicon: Add support for Hi3660 stub clocks
Julien Thierry
julien.thierry at arm.com
Fri Nov 3 10:37:34 PDT 2017
Hi Kaihua,
On 03/11/17 07:25, Kaihua Zhong wrote:
> Hi3660 has four stub clocks, which are big and LITTLE cluster clocks,
> GPU clock and DDR clock. These clocks ask MCU for frequency scaling
> by sending message through mailbox.
>
> This commit adds support for stub clocks, it requests the dedicated
> mailbox channel at initialization; then later uses this channel to send
> message to MCU to execute frequency scaling. The four stub clocks share
> the same mailbox channel, but every stub clock has its own command id so
> MCU can distinguish the requirement coming for which clock.
>
> A shared memory is used to present effective frequency value, so the
> clock driver uses I/O mapping for the memory and reads back rate value.
>
> Reviewed-by: Leo Yan <leo.yan at linaro.org>
> Signed-off-by: Kai Zhao <zhaokai1 at hisilicon.com>
> Signed-off-by: Kevin Wang <kevin.wangtao at hisilicon.com>
> Signed-off-by: Ruyi Wang <wangruyi at huawei.com>
> Signed-off-by: Kaihua Zhong <zhongkaihua at huawei.com>
> ---
> drivers/clk/hisilicon/Kconfig | 6 +
> drivers/clk/hisilicon/Makefile | 1 +
> drivers/clk/hisilicon/clk-hi3660-stub.c | 195 +++++++++++++++++++++++++++++++
> include/dt-bindings/clock/hi3660-clock.h | 7 ++
> 4 files changed, 209 insertions(+)
> create mode 100644 drivers/clk/hisilicon/clk-hi3660-stub.c
>
> diff --git a/drivers/clk/hisilicon/Kconfig b/drivers/clk/hisilicon/Kconfig
> index 7098bfd..1bd4355 100644
> --- a/drivers/clk/hisilicon/Kconfig
> +++ b/drivers/clk/hisilicon/Kconfig
> @@ -49,3 +49,9 @@ config STUB_CLK_HI6220
> default ARCH_HISI
> help
> Build the Hisilicon Hi6220 stub clock driver.
> +
> +config STUB_CLK_HI3660
> + bool "Hi3660 Stub Clock Driver"
> + depends on COMMON_CLK_HI3660 && MAILBOX
> + help
> + Build the Hisilicon Hi3660 stub clock driver.
> diff --git a/drivers/clk/hisilicon/Makefile b/drivers/clk/hisilicon/Makefile
> index 1e4c3dd..0a5b499 100644
> --- a/drivers/clk/hisilicon/Makefile
> +++ b/drivers/clk/hisilicon/Makefile
> @@ -14,3 +14,4 @@ obj-$(CONFIG_COMMON_CLK_HI3798CV200) += crg-hi3798cv200.o
> obj-$(CONFIG_COMMON_CLK_HI6220) += clk-hi6220.o
> obj-$(CONFIG_RESET_HISI) += reset.o
> obj-$(CONFIG_STUB_CLK_HI6220) += clk-hi6220-stub.o
> +obj-$(CONFIG_STUB_CLK_HI3660) += clk-hi3660-stub.o
> diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c
> new file mode 100644
> index 0000000..0a21c91
> --- /dev/null
> +++ b/drivers/clk/hisilicon/clk-hi3660-stub.c
> @@ -0,0 +1,195 @@
> +/*
> + * Hisilicon clock driver
> + *
> + * Copyright (c) 2013-2017 Hisilicon Limited.
> + * Copyright (c) 2017 Linaro Limited.
> + *
> + * Author: Kai Zhao <zhaokai1 at hisilicon.com>
> + * Author: Tao Wang <kevin.wangtao at hisilicon.com>
> + * Author: Leo Yan <leo.yan at linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <dt-bindings/clock/hi3660-clock.h>
> +
> +#define HI3660_STUB_CLOCK_DATA (0x70)
> +#define MHZ (1000 * 1000)
> +
> +#define DEFINE_CLK_STUB(_id, _cmd, _name) \
> + { \
> + .id = (_id), \
> + .cmd = (_cmd), \
> + .hw.init = &(struct clk_init_data) { \
> + .name = #_name, \
> + .ops = &hi3660_stub_clk_ops, \
> + .num_parents = 0, \
> + .flags = CLK_GET_RATE_NOCACHE, \
> + }, \
> + },
> +
> +#define to_stub_clk(_hw) container_of(_hw, struct hi3660_stub_clk, hw)
> +
> +struct hi3660_stub_clk_chan {
> + struct mbox_client cl;
> + struct mbox_chan *mbox;
> +};
> +
> +struct hi3660_stub_clk {
> + unsigned int id;
> + struct device *dev;
I don't understand why you need to keep this. The only place it is used
it for the debug message in hi3660_stub_clk_set_rate and you could get
the device pointer by doing chan->cl.dev since all the stub_clk point to
the same device.
> + struct clk_hw hw;
> + unsigned int cmd;
> + unsigned int msg[8];
> + unsigned int rate;
> +};
> +
> +static void __iomem *freq_reg;
> +static struct hi3660_stub_clk_chan *chan;
I would suggest having a slightly longer name than "chan" as this can
easily get shadowed which is bad for a non-local variable.
Also, maybe you could not declare it as a pointer and avoid the need for
kzalloc in the probe function.
> +
> +static unsigned long hi3660_stub_clk_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
> +
> + /*
> + * LPM3 writes back the CPU frequency in shared SRAM so read
> + * back the frequency.
> + */
> + stub_clk->rate = readl(freq_reg + (stub_clk->id << 2)) * MHZ;
> + return stub_clk->rate;
> +}
> +
> +static long hi3660_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *prate)
> +{
> + /*
> + * LPM3 handles rate rounding so just return whatever
> + * rate is requested.
> + */
> + return rate;
> +}
> +
> +static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
> +
> + stub_clk->msg[0] = stub_clk->cmd;
> + stub_clk->msg[1] = rate / MHZ;
> +
> + dev_dbg(stub_clk->dev, "set rate msg[0]=0x%x msg[1]=0x%x\n",
> + stub_clk->msg[0], stub_clk->msg[1]);
> +
> + mbox_send_message(chan->mbox, stub_clk->msg);
> + mbox_client_txdone(chan->mbox, 0);
> +
> + stub_clk->rate = rate;
> + return 0;
> +}
> +
> +static const struct clk_ops hi3660_stub_clk_ops = {
> + .recalc_rate = hi3660_stub_clk_recalc_rate,
> + .round_rate = hi3660_stub_clk_round_rate,
> + .set_rate = hi3660_stub_clk_set_rate,
> +};
> +
> +static struct hi3660_stub_clk hi3660_stub_clks[HI3660_CLK_STUB_NUM] = {
> + DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER0, 0x0001030A, "cpu-cluster.0")
> + DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER1, 0x0002030A, "cpu-cluster.1")
> + DEFINE_CLK_STUB(HI3660_CLK_STUB_GPU, 0x0003030A, "clk-g3d")
> + DEFINE_CLK_STUB(HI3660_CLK_STUB_DDR, 0x00040309, "clk-ddrc")
> +};
> +
> +static struct clk_hw *hi3660_stub_clk_hw_get(struct of_phandle_args *clkspec,
> + void *data)
> +{
> + unsigned int idx = clkspec->args[0];
> +
> + if (idx > HI3660_CLK_STUB_NUM) {
> + pr_err("%s: invalid index %u\n", __func__, idx);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + return &hi3660_stub_clks[idx].hw;
> +}
> +
> +static int hi3660_stub_clk_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct resource *res;
> + unsigned int i;
> + int ret;
> +
> + chan = devm_kzalloc(dev, sizeof(*chan), GFP_KERNEL);
> + if (!chan)
> + return -ENOMEM;
> +
> + /* Use mailbox client without blocking */
> + chan->cl.dev = dev;
> + chan->cl.tx_done = NULL;
> + chan->cl.tx_block = false;
> + chan->cl.knows_txdone = false;
> +
> + /* Allocate mailbox channel */
> + chan->mbox = mbox_request_channel(&chan->cl, 0);
> + if (IS_ERR(chan->mbox))
> + return PTR_ERR(chan->mbox);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + freq_reg = devm_ioremap(dev, res->start, resource_size(res));
> + if (IS_ERR(freq_reg))
> + return -ENOMEM;
> +
> + freq_reg += HI3660_STUB_CLOCK_DATA;
> +
> + for (i = 0; i < HI3660_CLK_STUB_NUM; i++) {
> + hi3660_stub_clks[i].dev = dev;
> + ret = devm_clk_hw_register(&pdev->dev, &hi3660_stub_clks[i].hw);
> + if (ret)
> + return ret;
> + }
> +
> + ret = of_clk_add_hw_provider(pdev->dev.of_node, hi3660_stub_clk_hw_get,
> + hi3660_stub_clks);
> + if (ret)
> + return ret;
> +
> + return 0;
Hmmm, you could just return ret here without needing the branch.
Cheers,
--
Julien Thierry
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