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Message-ID: <20171110040831.GA30162@leoy-linaro>
Date: Fri, 10 Nov 2017 12:08:31 +0800
From: Leo Yan <leo.yan@...aro.org>
To: Julien Thierry <julien.thierry@....com>
Cc: Kaihua Zhong <zhongkaihua@...wei.com>, mturquette@...libre.com,
sboyd@...eaurora.org, robh+dt@...nel.org, mark.rutland@....com,
xuwei5@...ilicon.com, catalin.marinas@....com, will.deacon@....com,
xuejiancheng@...ilicon.com, wenpan@...ilicon.com,
zhangfei.gao@...aro.org, guodong.xu@...aro.org,
chenjun14@...wei.com, linux-clk@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, suzhuangluan@...ilicon.com,
xuezhiliang@...ilicon.com, kevin.wangtao@...ilicon.com
Subject: Re: [PATCH 2/3] clk: hisilicon: Add support for Hi3660 stub clocks
Hi Julien,
On Fri, Nov 03, 2017 at 05:37:34PM +0000, Julien Thierry wrote:
> 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@...aro.org>
> >Signed-off-by: Kai Zhao <zhaokai1@...ilicon.com>
> >Signed-off-by: Kevin Wang <kevin.wangtao@...ilicon.com>
> >Signed-off-by: Ruyi Wang <wangruyi@...wei.com>
> >Signed-off-by: Kaihua Zhong <zhongkaihua@...wei.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@...ilicon.com>
> >+ * Author: Tao Wang <kevin.wangtao@...ilicon.com>
> >+ * Author: Leo Yan <leo.yan@...aro.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.
Kaihua might miss this email, so I checked all your comments; accept
these comments and will spin for next version patch.
Thank you for good suggestions.
Thanks,
Leo Yan
> >+ 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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