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Message-ID: <20190911113633.GR9720@e119886-lin.cambridge.arm.com>
Date: Wed, 11 Sep 2019 12:36:34 +0100
From: Andrew Murray <andrew.murray@....com>
To: Neil Armstrong <narmstrong@...libre.com>
Cc: khilman@...libre.com, bhelgaas@...gle.com,
lorenzo.pieralisi@....com, yue.wang@...ogic.com, kishon@...com,
repk@...plefau.lt, maz@...nel.org,
linux-amlogic@...ts.infradead.org, linux-pci@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] PCI: amlogic: meson: Add support for G12A
On Sun, Sep 08, 2019 at 01:42:55PM +0000, Neil Armstrong wrote:
> Add support for the Amlogic G12A SoC using a separate shared PHY.
>
> This adds support for fetching a PHY phandle and call the PHY init,
> reset and power on/off calls instead of writing in the PHY register or
> toggling the PHY reset line.
>
> The MIPI clock is also made optional since it is used for setting up
Is it worth indicating here that the MIPI clock is *only required* for
the G12A (or controllers with a shared phy)? It's still required for
AXG. It's not optional for G12A - it's ignored.
> the PHY reference clock chared with the DSI controller on AXG.
s/chared/shared/
>
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> ---
> drivers/pci/controller/dwc/pci-meson.c | 101 ++++++++++++++++++++-----
> 1 file changed, 84 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
> index ab79990798f8..3fadad381762 100644
> --- a/drivers/pci/controller/dwc/pci-meson.c
> +++ b/drivers/pci/controller/dwc/pci-meson.c
> @@ -16,6 +16,7 @@
> #include <linux/reset.h>
> #include <linux/resource.h>
> #include <linux/types.h>
> +#include <linux/phy/phy.h>
>
> #include "pcie-designware.h"
>
> @@ -96,12 +97,18 @@ struct meson_pcie_rc_reset {
> struct reset_control *apb;
> };
>
> +struct meson_pcie_param {
> + bool has_shared_phy;
> +};
> +
> struct meson_pcie {
> struct dw_pcie pci;
> struct meson_pcie_mem_res mem_res;
> struct meson_pcie_clk_res clk_res;
> struct meson_pcie_rc_reset mrst;
> struct gpio_desc *reset_gpio;
> + struct phy *phy;
> + const struct meson_pcie_param *param;
> };
>
> static struct reset_control *meson_pcie_get_reset(struct meson_pcie *mp,
> @@ -123,10 +130,12 @@ static int meson_pcie_get_resets(struct meson_pcie *mp)
> {
> struct meson_pcie_rc_reset *mrst = &mp->mrst;
>
> - mrst->phy = meson_pcie_get_reset(mp, "phy", PCIE_SHARED_RESET);
> - if (IS_ERR(mrst->phy))
> - return PTR_ERR(mrst->phy);
> - reset_control_deassert(mrst->phy);
> + if (!mp->param->has_shared_phy) {
> + mrst->phy = meson_pcie_get_reset(mp, "phy", PCIE_SHARED_RESET);
> + if (IS_ERR(mrst->phy))
> + return PTR_ERR(mrst->phy);
> + reset_control_deassert(mrst->phy);
> + }
>
> mrst->port = meson_pcie_get_reset(mp, "port", PCIE_NORMAL_RESET);
> if (IS_ERR(mrst->port))
> @@ -180,6 +189,9 @@ static int meson_pcie_get_mems(struct platform_device *pdev,
> if (IS_ERR(mp->mem_res.cfg_base))
> return PTR_ERR(mp->mem_res.cfg_base);
>
> + if (mp->param->has_shared_phy)
> + return 0;
> +
It may be more consistent if, rather than returning here, you wrapped
the following 3 lines by the if statement.
> /* Meson SoC has two PCI controllers use same phy register*/
I guess this comment should now be updated to refer to AXG?
> mp->mem_res.phy_base = meson_pcie_get_mem_shared(pdev, mp, "phy");
> if (IS_ERR(mp->mem_res.phy_base))
> @@ -188,19 +200,33 @@ static int meson_pcie_get_mems(struct platform_device *pdev,
> return 0;
> }
>
> -static void meson_pcie_power_on(struct meson_pcie *mp)
> +static int meson_pcie_power_on(struct meson_pcie *mp)
> {
> - writel(MESON_PCIE_PHY_POWERUP, mp->mem_res.phy_base);
> + int ret = 0;
> +
> + if (mp->param->has_shared_phy)
> + ret = phy_power_on(mp->phy);
I haven't seen any phy_[init/exit] calls, should there be any?
> + else
> + writel(MESON_PCIE_PHY_POWERUP, mp->mem_res.phy_base);
> +
> + return ret;
> }
>
> -static void meson_pcie_reset(struct meson_pcie *mp)
> +static int meson_pcie_reset(struct meson_pcie *mp)
> {
> struct meson_pcie_rc_reset *mrst = &mp->mrst;
> -
> - reset_control_assert(mrst->phy);
> - udelay(PCIE_RESET_DELAY);
> - reset_control_deassert(mrst->phy);
> - udelay(PCIE_RESET_DELAY);
> + int ret = 0;
> +
> + if (mp->param->has_shared_phy) {
> + ret = phy_reset(mp->phy);
> + if (ret)
> + return ret;
> + } else {
> + reset_control_assert(mrst->phy);
> + udelay(PCIE_RESET_DELAY);
> + reset_control_deassert(mrst->phy);
> + udelay(PCIE_RESET_DELAY);
> + }
>
> reset_control_assert(mrst->port);
> reset_control_assert(mrst->apb);
> @@ -208,6 +234,8 @@ static void meson_pcie_reset(struct meson_pcie *mp)
> reset_control_deassert(mrst->port);
> reset_control_deassert(mrst->apb);
> udelay(PCIE_RESET_DELAY);
> +
> + return 0;
> }
>
> static inline struct clk *meson_pcie_probe_clock(struct device *dev,
> @@ -250,9 +278,11 @@ static int meson_pcie_probe_clocks(struct meson_pcie *mp)
> if (IS_ERR(res->port_clk))
> return PTR_ERR(res->port_clk);
>
> - res->mipi_gate = meson_pcie_probe_clock(dev, "mipi", 0);
> - if (IS_ERR(res->mipi_gate))
> - return PTR_ERR(res->mipi_gate);
> + if (!mp->param->has_shared_phy) {
> + res->mipi_gate = meson_pcie_probe_clock(dev, "mipi", 0);
> + if (IS_ERR(res->mipi_gate))
> + return PTR_ERR(res->mipi_gate);
> + }
>
> res->general_clk = meson_pcie_probe_clock(dev, "general", 0);
> if (IS_ERR(res->general_clk))
> @@ -524,6 +554,7 @@ static const struct dw_pcie_ops dw_pcie_ops = {
>
> static int meson_pcie_probe(struct platform_device *pdev)
> {
> + const struct meson_pcie_param *match_data;
> struct device *dev = &pdev->dev;
> struct dw_pcie *pci;
> struct meson_pcie *mp;
> @@ -537,6 +568,20 @@ static int meson_pcie_probe(struct platform_device *pdev)
> pci->dev = dev;
> pci->ops = &dw_pcie_ops;
>
> + match_data = of_device_get_match_data(dev);
> + if (!match_data) {
> + dev_err(dev, "failed to get match data\n");
> + return -ENODEV;
> + }
> + mp->param = match_data;
> +
> + if (mp->param->has_shared_phy) {
> + mp->phy = devm_phy_get(dev, "pcie");
> + if (IS_ERR(mp->phy)) {
> + return PTR_ERR(mp->phy);
> + }
> + }
> +
> mp->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> if (IS_ERR(mp->reset_gpio)) {
> dev_err(dev, "get reset gpio failed\n");
> @@ -555,8 +600,17 @@ static int meson_pcie_probe(struct platform_device *pdev)
> return ret;
> }
>
> - meson_pcie_power_on(mp);
> - meson_pcie_reset(mp);
> + ret = meson_pcie_power_on(mp);
> + if (ret) {
> + dev_err(dev, "phy power on failed, %d\n", ret);
> + return ret;
> + }
> +
> + ret = meson_pcie_reset(mp);
> + if (ret) {
> + dev_err(dev, "reset failed, %d\n", ret);
> + return ret;
> + }
>
> ret = meson_pcie_probe_clocks(mp);
> if (ret) {
> @@ -575,9 +629,22 @@ static int meson_pcie_probe(struct platform_device *pdev)
> return 0;
> }
>
> +static struct meson_pcie_param meson_pcie_axg_param = {
> + .has_shared_phy = false,
> +};
> +
> +static struct meson_pcie_param meson_pcie_g12a_param = {
> + .has_shared_phy = true,
> +};
> +
> static const struct of_device_id meson_pcie_of_match[] = {
> {
> .compatible = "amlogic,axg-pcie",
> + .data = &meson_pcie_axg_param,
> + },
> + {
> + .compatible = "amlogic,g12a-pcie",
> + .data = &meson_pcie_g12a_param,
Here, we hard-code knowledge about the SOCs regarding if they have shared phys
or not. I guess the alternative would have been to assume there is a shared
phy if the DT has a phandle for it. I.e. instead of mp->param->has_shared_phy
everywhere you could test for mp->phy. Though I guess at least with the
current approach you guard against bad DTs, this seems OK.
Thanks,
Andrew Murray
> },
> {},
> };
> --
> 2.17.1
>
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