On Mon, Dec 7, 2015 at 5:36 PM, Maxime Ripard
[off-list ref] wrote:

Hi,

On Thu, Dec 03, 2015 at 03:05:30PM +0800, Chen-Yu Tsai wrote:

quoted

The APBS clock on sun9i is the same as the APB0 clock on sun8i. With
sun9i we are supporting the PRCM clocks by using CLK_OF_DECLARE,
instead of through a PRCM mfd device and subdevices for each clock
and reset control. As such we need a CLK_OF_DECLARE version of
the sun8i-a23-apb0-clk driver.

Also, build it for sun9i/A80, and not just for configurations with
MFD_SUN6I_PRCM enabled.

Signed-off-by: Chen-Yu Tsai <redacted>
---

Changes since v4:

  - Keep building clk-sun8i-apb0 for SUN6I_MFD_PRCM.

  - Add an error message and comment for when of_io_request_and_map()
    fails. of_io_request_and_map() merges a bunch of errors into -EINVAL,
    so this might not be the best approach. But I think having an error
    message when we know something is wrong (-EBUSY, -ENOMEM) is better.

---
 drivers/clk/sunxi/Makefile         |  1 +
 drivers/clk/sunxi/clk-sun8i-apb0.c | 80 ++++++++++++++++++++++++++++++++------
 2 files changed, 69 insertions(+), 12 deletions(-)

diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
index 103efab05ca8..ccf21ba3b6b0 100644
--- a/drivers/clk/sunxi/Makefile
+++ b/drivers/clk/sunxi/Makefile

@@ -15,6 +15,7 @@ obj-y += clk-sun9i-core.o
 obj-y += clk-sun9i-mmc.o
 obj-y += clk-usb.o

+obj-$(CONFIG_MACH_SUN9I) += clk-sun8i-apb0.o
 obj-$(CONFIG_MACH_SUN9I) += clk-sun9i-cpus.o

 obj-$(CONFIG_MFD_SUN6I_PRCM) += \

diff --git a/drivers/clk/sunxi/clk-sun8i-apb0.c b/drivers/clk/sunxi/clk-sun8i-apb0.c
index 7ae5d2c2cde1..7ba61103a6f5 100644
--- a/drivers/clk/sunxi/clk-sun8i-apb0.c
+++ b/drivers/clk/sunxi/clk-sun8i-apb0.c

@@ -17,13 +17,77 @@
 #include <linux/clk-provider.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>

+static struct clk *sun8i_a23_apb0_register(struct device_node *node,
+                                        void __iomem *reg)
+{
+     const char *clk_name = node->name;
+     const char *clk_parent;
+     struct clk *clk;
+     int ret;
+
+     clk_parent = of_clk_get_parent_name(node, 0);
+     if (!clk_parent)
+             return ERR_PTR(-EINVAL);
+
+     of_property_read_string(node, "clock-output-names", &clk_name);
+
+     /* The A23 APB0 clock is a standard 2 bit wide divider clock */
+     clk = clk_register_divider(NULL, clk_name, clk_parent, 0, reg,
+                                0, 2, CLK_DIVIDER_POWER_OF_TWO, NULL);
+     if (IS_ERR(clk))
+             return clk;
+
+     ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
+     if (ret)
+             goto err_unregister;
+
+     return clk;
+
+err_unregister:
+     clk_unregister_divider(clk);
+
+     return ERR_PTR(ret);
+}
+
+static void sun8i_a23_apb0_setup(struct device_node *node)
+{
+     void __iomem *reg;
+     struct resource res;
+     struct clk *clk;
+
+     reg = of_io_request_and_map(node, 0, of_node_full_name(node));
+     if (IS_ERR(reg)) {
+             /*
+              * This happens with clk nodes instantiated through mfd,
+              * as those do not have their resources assigned in the
+              * device tree. Do not print an error in this case.
+              */
+             if (PTR_ERR(reg) != -EINVAL)
+                     pr_err("Could not get registers for a23-apb0-clk\n");

This is not the only case you have to take into account.

There's also the case when you have a regular clock (and by regular I
mean that is not in the PRCM) that will be probed by the
CLK_OF_DECLARE mechanism and then later by the device model.

In such a case, the second of_io_request_and_map will fail, and you
will have an error returned that you do not ignore at the moment.

Right. It will return -EBUSY. But ignoring it and returning 0 is telling
the driver core that the device successfully binded. I think this is
wrong.

Normal clocks should be in the "clocks" node, and wouldn't be probed a
second time through the device model, would it? Am I missing something?

ChenYu