Re: [RFC v4 06/10] pwm: dwc: split pci out of core driver

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On 19/08/2022 14:38, Jarkko Nikula wrote:
Hi

On 8/17/22 00:14, Ben Dooks wrote:
Moving towards adding non-pci support for the driver, move the pci
parts out of the core into their own module. This is partly due to
the module_driver() code only being allowed once in a module and also
to avoid a number of #ifdef if we build a single file in a system
without pci support.

Signed-off-by: Ben Dooks <ben.dooks@xxxxxxxxxx>
---

I quickly tested this on Intel Elkhart and didn't notice any regression. A few comments below.

  drivers/pwm/Kconfig       |  14 +++-
  drivers/pwm/Makefile      |   1 +
  drivers/pwm/pwm-dwc-pci.c | 133 ++++++++++++++++++++++++++++++++
  drivers/pwm/pwm-dwc.c     | 158 +-------------------------------------
  drivers/pwm/pwm-dwc.h     |  58 ++++++++++++++
  5 files changed, 207 insertions(+), 157 deletions(-)
  create mode 100644 drivers/pwm/pwm-dwc-pci.c
  create mode 100644 drivers/pwm/pwm-dwc.h

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 3f3c53af4a56..a9f1c554db2b 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -175,15 +175,23 @@ config PWM_CROS_EC
        Controller.
  config PWM_DWC
-    tristate "DesignWare PWM Controller"
-    depends on PCI || COMPILE_TEST
+    tristate "DesignWare PWM Controller core"
      depends on HAS_IOMEM
      help
-      PWM driver for Synopsys DWC PWM Controller attached to a PCI bus.
+      PWM driver for Synopsys DWC PWM Controller.
        To compile this driver as a module, choose M here: the module
        will be called pwm-dwc.
+config PWM_DWC_PCI
+    tristate "DesignWare PWM Controller core"

Same text as core part has. How about "DesignWare PWM Controller PCI driver"?

Thanks, did notice a couple of kconfig issues so will look at that.


+    depends on PWM_DWC && HAS_IOMEM && PCI
+    help
+      PWM driver for Synopsys DWC PWM Controller attached to a PCI bus.
+
+      To compile this driver as a module, choose M here: the module
+      will be called pwm-dwc-pci.
+
  config PWM_EP93XX
      tristate "Cirrus Logic EP93xx PWM support"
      depends on ARCH_EP93XX || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 7bf1a29f02b8..a70d36623129 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_PWM_CLPS711X)    += pwm-clps711x.o
  obj-$(CONFIG_PWM_CRC)        += pwm-crc.o
  obj-$(CONFIG_PWM_CROS_EC)    += pwm-cros-ec.o
  obj-$(CONFIG_PWM_DWC)        += pwm-dwc.o
+obj-$(CONFIG_PWM_DWC_PCI)    += pwm-dwc-pci.o
  obj-$(CONFIG_PWM_EP93XX)    += pwm-ep93xx.o
  obj-$(CONFIG_PWM_FSL_FTM)    += pwm-fsl-ftm.o
  obj-$(CONFIG_PWM_HIBVT)        += pwm-hibvt.o
diff --git a/drivers/pwm/pwm-dwc-pci.c b/drivers/pwm/pwm-dwc-pci.c
new file mode 100644
index 000000000000..2213d0e7f3c8
--- /dev/null
+++ b/drivers/pwm/pwm-dwc-pci.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DesignWare PWM Controller driver (PCI part)
+ *
+ * Copyright (C) 2018-2020 Intel Corporation
+ *
+ * Author: Felipe Balbi (Intel)
+ * Author: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
+ * Author: Raymond Tan <raymond.tan@xxxxxxxxx>
+ *
+ * Limitations:
+ * - The hardware cannot generate a 0 % or 100 % duty cycle. Both high and low
+ *   periods are one or more input clock periods long.
+ */
+

I think this is more common limitation rather than PCI part.

The PCI is based off an core without the support, it is added
as a build option as of (IIRC) the 2.13 core.


--- a/drivers/pwm/pwm-dwc.c
+++ b/drivers/pwm/pwm-dwc.c
@@ -1,16 +1,12 @@
  // SPDX-License-Identifier: GPL-2.0
  /*
- * DesignWare PWM Controller driver
+ * DesignWare PWM Controller driver core
   *
   * Copyright (C) 2018-2020 Intel Corporation
   *
   * Author: Felipe Balbi (Intel)
   * Author: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
   * Author: Raymond Tan <raymond.tan@xxxxxxxxx>
- *
- * Limitations:
- * - The hardware cannot generate a 0 % or 100 % duty cycle. Both high and low
- *   periods are one or more input clock periods long.
   */

Relates to previous comment, is there reason why this limitation is removed from the core part?

See above.


--- /dev/null
+++ b/drivers/pwm/pwm-dwc.h
+#define DWC_CLK_PERIOD_NS    10

Perhaps this addition can be removed if patch 7/10 goes before this patch? It's anyway specific to PCI part only.

Will look into that




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