linux-kernel - Re: [PATCH V4 1/3] pci: Add PCIe driver for Samsung Exynos

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Message-ID: <51C2D260.6000303@st.com>
Date:	Thu, 20 Jun 2013 15:28:56 +0530
From:	Pratyush Anand <pratyush.anand@...com>
To:	Arnd Bergmann <arnd@...db.de>, Jingoo Han <jg1.han@...sung.com>
Cc:	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Bjorn Helgaas' <bhelgaas@...gle.com>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	'Grant Likely' <grant.likely@...retlab.ca>,
	'Andrew Murray' <andrew.murray@....com>,
	'Thomas Petazzoni' <thomas.petazzoni@...e-electrons.com>,
	'Thierry Reding' <thierry.reding@...onic-design.de>,
	'Jason Gunthorpe' <jgunthorpe@...idianresearch.com>,
	'Surendranath Gurivireddy Balla' <suren.reddy@...sung.com>,
	'Siva Reddy Kallam' <siva.kallam@...sung.com>,
	'Thomas Abraham' <thomas.abraham@...aro.org>,
	Mohit KUMAR <Mohit.KUMAR@...com>
Subject: Re: [PATCH V4 1/3] pci: Add PCIe driver for Samsung Exynos

On 6/13/2013 7:48 PM, Arnd Bergmann wrote:
> On Thursday 13 June 2013 22:18:50 Jingoo Han wrote:
>> >On Wednesday, June 12, 2013 8:23 PM, Arnd Bergmann wrote:
>>> > >On Wednesday 12 June 2013 19:19:05 Jingoo Han wrote:
>>>> > > >+
>>>> > > >+/* synopsis specific PCIE configuration registers*/
>>>> > > >+#define PCIE_PORT_LINK_CONTROL		0x710
>>>> > > >+#define PORT_LINK_MODE_MASK		(0x3f << 16)
>>>> > > >+#define PORT_LINK_MODE_4_LANES		(0x7 << 16)
>>> > >
>>> > >Do you mean this is a "Synopsys" designware part? In that case it
>>> > >should really not be called "exynos-pcie" but "designware-pcie"
>>> > >and you should make sure that the driver makes no assumptions about
>>> > >the platform. A lot of other platforms also use designware
>>> > >parts and should be able to reuse this driver.
>> >
>> >Sorry, I don't think so.
>> >Only core block is a "Synopsys" designware part IP block,
>> >other parts are Exynos-specific.
>> >So, it is hard to share with other PCIe IPs using synopsis core.
> Just call it synopsys anyway and put a comment in to explain this.
> That should be enough for the next person with a synopsys PCI core
> to reuse your code and split out the exynos specific parts into a
> separate file.
>

I agree to Arnd that this patch should be split. I had worked in past 
with SPEAr PCIe which also had designware PCIe IP. I see some code which 
will fit both in SPEAr as well as in exynos. Unfortunately, I was not 
able to get SPEAr driver pushed to mainline, as I moved to some other 
project and got heavily occupied.

Last patch is here:

https://patchwork.kernel.org/patch/1661441/

Infact, these functions should be common to all arm platforms.

sys_to_pcie
cfg_read
cfg_write

Following functions should be common to all designware based driver (at 
least they are same in SPEAr)

exynos_pcie_prog_viewport_cfg0
exynos_pcie_prog_viewport_cfg1
exynos_pcie_rd_other_conf
exynos_pcie_wr_other_conf
exynos_pcie_setup
exynos_pcie_valid_config
exynos_pcie_rd_conf
exynos_pcie_wd_conf
exynos_pcie_scan_bus
exynos_pcie_map_irq
add_pcie_port (after a bit of generalization)
exynos_pcie_probe
exynos_pcie_remove



Following should be specific to exynos:

exynos_pcie_rd_own_conf
exynos_pcie_wr_own_conf
exynos_pcie_link_up
exynos_pcie_setup_rc
exynos_pcie_assert_core_reset
exynos_pcie_deassert_core_reset
exynos_pcie_assert_phy_reset
exynos_pcie_deassert_phy_reset
exynos_pcie_init_phy
exynos_pcie_assert_reset
exynos_pcie_establish_link
exynos_pcie_host_init



struct pcie_port_info and struct pcie_port can also be standardized.

Regards
Pratyush
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