Re: [PATCH v1 1/1] clk: npcm7xx: get fixed clocks from DT

Hi Stephan,

Thanks for all the comments!

This patch include one change so it's one commit.
This clock module includes 4 PLLs and then a tree of muxes and dividers.
All muxes and dividers are preset before Linux boots. The presetting can
change according to the board.
Linux drivers need to know what the frequencies are, but they can not
change it,
so this whole driver is intended as read only mechanism for clocks.

On the first version which was up-streamed the PLLs input clk value was
defined inside the driver.

After the review I was asked that the fixed clock will be on the DT. This
is this fix.


This patch was submitted, but not pushed to Linux:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1610776.html

Meanwhile first version was pushed to the Kernel, So recreate a patch that
is relative between the two patches.


More comments inline..



On Fri, Nov 30, 2018 at 2:23 AM Stephen Boyd [off-list ref] wrote:

Quoting tali.perry1@gmail.com (2018-11-11 05:47:12)

quoted

From: Tali Perry <tali.perry1@gmail.com>

Nuvoton NPCM7XX Clock Controller
fix base address and of_clk_get_by_name error handling.
    Also update error messages to be more informative.

    In case clk_base allocation is erronoeous the return value is null.
    Also fix handling of of_clk_get_by_name returns an error.
    Print a better error message pointing to the dt-binding documention.

This patch is re-submitted since it was already pushed to main
(just the diff, without the full driver which is already in
master branch.)


Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wei Yongjun <redacted>

I don't know what's going on with this patch. Is it something new? Can
you break it up into logical changes and submit them with proper commit
text? The signoff chain is also odd. Can you follow
Documentation/process/submitting-patches.rst?

quoted

---
 drivers/clk/clk-npcm7xx.c | 99

+++++++++++++++++++++++++++++++++++------------

quoted

 1 file changed, 75 insertions(+), 24 deletions(-)

diff --git a/drivers/clk/clk-npcm7xx.c b/drivers/clk/clk-npcm7xx.c
index 740af90a9508..91a937720f4e 100644
--- a/drivers/clk/clk-npcm7xx.c
+++ b/drivers/clk/clk-npcm7xx.c

@@ -7,17 +7,26 @@
  * Copyright (C) 2018 Nuvoton Technologies tali.perry@nuvoton.com
  */

-#include <linux/module.h>
-#include <linux/clk-provider.h>
-#include <linux/io.h>
-#include <linux/kernel.h>
-#include <linux/of.h>
-#include <linux/of_address.h>
-#include <linux/slab.h>
-#include <linux/err.h>
-#include <linux/bitfield.h>
-
-#include <dt-bindings/clock/nuvoton,npcm7xx-clock.h>
+
+
+
+ #include <linux/module.h>
+ #include <linux/clk.h>
+ #include <linux/clk-provider.h>
+ #include <linux/device.h>
+ #include <linux/io.h>
+ #include <linux/kernel.h>
+ #include <linux/of.h>
+ #include <linux/of_device.h>
+ #include <linux/of_platform.h>
+ #include <linux/of_address.h>
+ #include <linux/platform_device.h>
+ #include <linux/slab.h>
+ #include <linux/err.h>
+ #include <linux/rational.h>
+ #include <linux/bitfield.h>
+ #include <dt-bindings/clock/nuvoton,npcm7xx-clock.h>

Is any of this hunk necessary or relevant to the subject of this patch?

quoted

+

 struct npcm7xx_clk_pll {

@@ -44,7 +56,8 @@ static unsigned long

npcm7xx_clk_pll_recalc_rate(struct clk_hw *hw,

quoted

        u64 ret;

        if (parent_rate == 0) {
-               pr_err("%s: parent rate is zero", __func__);
+               pr_err("%s: parent rate is zero. reg=%x\n", __func__,
+                       (u32)(pll->pllcon));

Maybe you should print clk name instead of register?

Tali: There are only 4 pllcon registers. I don't mind if it's the address
and not the name.

quoted

                return 0;
        }

@@ -61,13 +74,12 @@ static unsigned long

npcm7xx_clk_pll_recalc_rate(struct clk_hw *hw,

quoted

        return ret;
 }

-static const struct clk_ops npcm7xx_clk_pll_ops = {
+const struct clk_ops npcm7xx_clk_pll_ops = {

Why?

Tali: I will return the static.

quoted

        .recalc_rate = npcm7xx_clk_pll_recalc_rate,
 };

-static struct clk_hw *
-npcm7xx_clk_register_pll(void __iomem *pllcon, const char *name,
-                        const char *parent_name, unsigned long flags)
+static struct clk_hw *npcm7xx_clk_register_pll(void __iomem *pllcon,
+               const char *name, const char *parent_name, unsigned long

flags)

quoted

 {
        struct npcm7xx_clk_pll *pll;
        struct clk_init_data init;

@@ -78,7 +90,8 @@ npcm7xx_clk_register_pll(void __iomem *pllcon, const

char *name,

quoted

        if (!pll)
                return ERR_PTR(-ENOMEM);

-       pr_debug("%s reg, name=%s, p=%s\n", __func__, name, parent_name);
+       pr_debug("%s reg, reg=0x%x, name=%s, p=%s\n",
+               __func__, (unsigned int)pllcon, name, parent_name);

What's going on here? Why cast?

Tali: I will remove this print all together.

quoted

        init.name = name;
        init.ops = &npcm7xx_clk_pll_ops;

@@ -544,9 +557,11 @@ static void __init npcm7xx_clk_init(struct

device_node *clk_np)

quoted

        void __iomem *clk_base;
        struct resource res;
        struct clk_hw *hw;
+       struct clk *clk;
        int ret;
        int i;

+       clk_base = NULL;

Why?

Tali: to init it. If DT is badly defined the value will remain NULL.

quoted

        ret = of_address_to_resource(clk_np, 0, &res);
        if (ret) {
                pr_err("%s: failed to get resource, ret %d\n",

clk_np->name,

quoted

@@ -560,14 +575,44 @@ static void __init npcm7xx_clk_init(struct

device_node *clk_np)

quoted

        npcm7xx_clk_data = kzalloc(sizeof(*npcm7xx_clk_data->hws) *
                NPCM7XX_NUM_CLOCKS + sizeof(npcm7xx_clk_data),

GFP_KERNEL);

quoted

-       if (!npcm7xx_clk_data)
+
+       npcm7xx_clk_data->num = 0;

kzalloc already does that initialization to 0 for you.

quoted

+
+       if (!npcm7xx_clk_data->hws) {
+               pr_err("Can't alloc npcm7xx_clk_data\n");

We don't need allocation error messages.

quoted

                goto npcm7xx_init_np_err;
+       }

        npcm7xx_clk_data->num = NPCM7XX_NUM_CLOCKS;

        for (i = 0; i < NPCM7XX_NUM_CLOCKS; i++)
                npcm7xx_clk_data->hws[i] = ERR_PTR(-EPROBE_DEFER);

+       /* Read fixed clocks. These 3 clocks must be defined in DT */
+       clk = of_clk_get_by_name(clk_np, NPCM7XX_CLK_S_REFCLK);
+       if (IS_ERR(clk)) {
+               pr_err("failed to find external REFCLK on device tree,

err=%ld\n",

quoted

+                       PTR_ERR(clk));
+               clk_put(clk);
+               goto npcm7xx_init_fail_no_clk_on_dt;
+       }
+
+       clk = of_clk_get_by_name(clk_np, NPCM7XX_CLK_S_SYSBYPCK);
+       if (IS_ERR(clk)) {
+               pr_err("failed to find external SYSBYPCK on device tree,

err=%ld\n",

quoted

+                       PTR_ERR(clk));
+               clk_put(clk);
+               goto npcm7xx_init_fail_no_clk_on_dt;
+       }
+
+       clk = of_clk_get_by_name(clk_np, NPCM7XX_CLK_S_MCBYPCK);
+       if (IS_ERR(clk)) {
+               pr_err("failed to find external MCBYPCK on device tree,

err=%ld\n",

quoted

+                       PTR_ERR(clk));
+               clk_put(clk);
+               goto npcm7xx_init_fail_no_clk_on_dt;
+       }

I assume the DTS is not shipped?

Tali: DTS for npcm is shipped in a separate patchset.

quoted

+
        /* Register plls */
        for (i = 0; i < ARRAY_SIZE(npcm7xx_plls); i++) {
                const struct npcm7xx_clk_pll_data *pll_data =

&npcm7xx_plls[i];

quoted

@@ -584,16 +629,16 @@ static void __init npcm7xx_clk_init(struct

device_node *clk_np)

quoted

        }

        /* Register fixed dividers */
-       hw = clk_hw_register_fixed_factor(NULL, NPCM7XX_CLK_S_PLL1_DIV2,
+       clk = clk_register_fixed_factor(NULL, NPCM7XX_CLK_S_PLL1_DIV2,

This is going backwards. Please use clk_hw APIs.

Tali: Will fix.

quoted

                        NPCM7XX_CLK_S_PLL1, 0, 1, 2);
-       if (IS_ERR(hw)) {
+       if (IS_ERR(clk)) {
                pr_err("npcm7xx_clk: Can't register fixed div\n");
                goto npcm7xx_init_fail;
        }

-       hw = clk_hw_register_fixed_factor(NULL, NPCM7XX_CLK_S_PLL2_DIV2,
+       clk = clk_register_fixed_factor(NULL, NPCM7XX_CLK_S_PLL2_DIV2,
                        NPCM7XX_CLK_S_PLL2, 0, 1, 2);
-       if (IS_ERR(hw)) {
+       if (IS_ERR(clk)) {
                pr_err("npcm7xx_clk: Can't register div2\n");
                goto npcm7xx_init_fail;
        }

@@ -646,11 +691,17 @@ static void __init npcm7xx_clk_init(struct

device_node *clk_np)

quoted

        return;

+npcm7xx_init_fail_no_clk_on_dt:
+       pr_err("see Documentation/devicetree/bindings/clock/");
+       pr_err("nuvoton,npcm750-clk.txt  for details\n");
 npcm7xx_init_fail:
-       kfree(npcm7xx_clk_data->hws);
+       if (npcm7xx_clk_data->num)
+               kfree(npcm7xx_clk_data->hws);
 npcm7xx_init_np_err:
-       iounmap(clk_base);
+       if (clk_base != NULL)
+               iounmap(clk_base);
 npcm7xx_init_error:
        of_node_put(clk_np);
+       pr_err("clk setup fail\n");

Is this hunk of changes related to the subject of this patch? I don't
think it is, so it just leads to more confusion.

Tali: I added a goto option for the case that the DTS doesn't have the
reference clocks this module needs.