[PATCH v5 2/6] phy: cdns-dphy: Add Rx support
Pratyush Yadav
p.yadav at ti.com
Fri Sep 17 10:28:11 PDT 2021
+Rob
On 16/09/21 12:22PM, Paul Kocialkowski wrote:
> Hi,
>
> On Fri 03 Sep 21, 00:25, Pratyush Yadav wrote:
> > The Cadence DPHY can be used to receive image data over the CSI-2
> > protocol. Add support for Rx mode. The programming sequence differs from
> > the Tx mode so it is added as a separate set of hooks to isolate the two
> > paths. The mode in which the DPHY has to be used is selected based on
> > the compatible.
>
> I just realized that I didn't follow-up on a previous revision on the debate
> about using the phy sub-mode to distinguish between rx/tx.
>
> I see that you've been using a dedicated compatible, but I'm not sure this is a
> good fit either. My understanding is that the compatible should describe a group
> of register-compatible revisions of a hardware component, not how the hardware
> is used specifically. I guess the distinction between rx/tx falls under
> the latter rather than the former.
I am not sure if that is the case. For example, we use "ti,am654-ospi"
for Cadence Quadspi controller. The default compatible, "cdns,qspi-nor",
only supports Quad SPI (4 lines). The "ti,am654-ospi" compatible also
supports Octal SPI (8 lines).
In addition, I feel like the Rx DPHY is almost a different type of
device from a Tx DPHY. The programming sequence is completely different,
the clocks required are different, etc. So I think using a different
compatible for Rx mode makes sense.
Rob, what do you think?
>
> I just sent out a patch in my Allwinner MIPI CSI-2+ISP series adding
> a specific direction property:
> - https://lists.infradead.org/pipermail/linux-phy/2021-September/001420.html
> - https://lists.infradead.org/pipermail/linux-phy/2021-September/001421.html
>
> Which I feel is a more appropriate solution to implement the distinction.
>
> What do you think?
>
> Cheers,
>
> Paul
>
> > Signed-off-by: Pratyush Yadav <p.yadav at ti.com>
> >
> > ---
> >
> > Changes in v5:
> > - Use the new cdns_dphy_info to specify PHY ops.
> > - Re-order include in alphabetical order.
> > - Make bands const.
> > - Drop num_bands.
> > - Make i, lanes unsigned.
> > - Drop the maximum check in cdns_dphy_rx_get_band_ctrl(). Let the loop
> > complete and return -EOPNOTSUPP when we reach the end.
> > - Drop the "rate < bands[i].min_rate" check since the bands are in
> > ascending order.
> > - Move data_lane_ctrl to start of function and make it static const.
> >
> > Changes in v4:
> > - Drop the submode parts. Use a different compatible for the Rx ops.
> > - Make bands and num_bands static.
> >
> > Changes in v3:
> > - Use a table to select the band.
> > - Use a table to poll the data lane ready bits.
> > - Multiply the DPHY HS clock rate by 2 to get the bit rate since the
> > clock is DDR.
> >
> > drivers/phy/cadence/cdns-dphy.c | 182 ++++++++++++++++++++++++++++++++
> > 1 file changed, 182 insertions(+)
> >
> > diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
> > index e2c2b27c6539..9a4c1c684e9a 100644
> > --- a/drivers/phy/cadence/cdns-dphy.c
> > +++ b/drivers/phy/cadence/cdns-dphy.c
> > @@ -1,11 +1,14 @@
> > // SPDX-License-Identifier: GPL-2.0+
> > /*
> > * Copyright: 2017-2018 Cadence Design Systems, Inc.
> > + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
> > */
> >
> > +#include <linux/bitfield.h>
> > #include <linux/bitops.h>
> > #include <linux/clk.h>
> > #include <linux/io.h>
> > +#include <linux/iopoll.h>
> > #include <linux/module.h>
> > #include <linux/of_address.h>
> > #include <linux/of_device.h>
> > @@ -25,10 +28,14 @@
> > #define DPHY_PMA_RCLK(reg) (0x600 + (reg))
> > #define DPHY_PMA_RDATA(lane, reg) (0x700 + ((lane) * 0x100) + (reg))
> > #define DPHY_PCS(reg) (0xb00 + (reg))
> > +#define DPHY_ISO(reg) (0xc00 + (reg))
> >
> > #define DPHY_CMN_SSM DPHY_PMA_CMN(0x20)
> > #define DPHY_CMN_SSM_EN BIT(0)
> > +#define DPHY_CMN_RX_BANDGAP_TIMER_MASK GENMASK(8, 1)
> > #define DPHY_CMN_TX_MODE_EN BIT(9)
> > +#define DPHY_CMN_RX_MODE_EN BIT(10)
> > +#define DPHY_CMN_RX_BANDGAP_TIMER 0x14
> >
> > #define DPHY_CMN_PWM DPHY_PMA_CMN(0x40)
> > #define DPHY_CMN_PWM_DIV(x) ((x) << 20)
> > @@ -45,10 +52,27 @@
> > #define DPHY_CMN_OPDIV_FROM_REG BIT(6)
> > #define DPHY_CMN_OPDIV(x) ((x) << 7)
> >
> > +#define DPHY_BAND_CFG DPHY_PCS(0x0)
> > +#define DPHY_BAND_CFG_LEFT_BAND GENMASK(4, 0)
> > +#define DPHY_BAND_CFG_RIGHT_BAND GENMASK(9, 5)
> > +
> > #define DPHY_PSM_CFG DPHY_PCS(0x4)
> > #define DPHY_PSM_CFG_FROM_REG BIT(0)
> > #define DPHY_PSM_CLK_DIV(x) ((x) << 1)
> >
> > +#define DPHY_POWER_ISLAND_EN_DATA DPHY_PCS(0x8)
> > +#define DPHY_POWER_ISLAND_EN_DATA_VAL 0xaaaaaaaa
> > +#define DPHY_POWER_ISLAND_EN_CLK DPHY_PCS(0xc)
> > +#define DPHY_POWER_ISLAND_EN_CLK_VAL 0xaa
> > +
> > +#define DPHY_ISO_CL_CTRL_L DPHY_ISO(0x10)
> > +#define DPHY_ISO_DL_CTRL_L0 DPHY_ISO(0x14)
> > +#define DPHY_ISO_DL_CTRL_L1 DPHY_ISO(0x20)
> > +#define DPHY_ISO_DL_CTRL_L2 DPHY_ISO(0x30)
> > +#define DPHY_ISO_DL_CTRL_L3 DPHY_ISO(0x3c)
> > +#define DPHY_ISO_LANE_READY_BIT 0
> > +#define DPHY_ISO_LANE_READY_TIMEOUT_MS 100UL
> > +
> > #define DSI_HBP_FRAME_OVERHEAD 12
> > #define DSI_HSA_FRAME_OVERHEAD 14
> > #define DSI_HFP_FRAME_OVERHEAD 6
> > @@ -57,6 +81,9 @@
> > #define DSI_NULL_FRAME_OVERHEAD 6
> > #define DSI_EOT_PKT_SIZE 4
> >
> > +#define DPHY_LANES_MIN 1
> > +#define DPHY_LANES_MAX 4
> > +
> > struct cdns_dphy_cfg {
> > u8 pll_ipdiv;
> > u8 pll_opdiv;
> > @@ -105,6 +132,20 @@ struct cdns_dphy {
> > struct phy *phy;
> > };
> >
> > +struct cdns_dphy_rx_band {
> > + unsigned int min_rate;
> > + unsigned int max_rate;
> > +};
> > +
> > +/* Order of bands is important since the index is the band number. */
> > +static const struct cdns_dphy_rx_band bands[] = {
> > + {80, 100}, {100, 120}, {120, 160}, {160, 200}, {200, 240},
> > + {240, 280}, {280, 320}, {320, 360}, {360, 400}, {400, 480},
> > + {480, 560}, {560, 640}, {640, 720}, {720, 800}, {800, 880},
> > + {880, 1040}, {1040, 1200}, {1200, 1350}, {1350, 1500}, {1500, 1750},
> > + {1750, 2000}, {2000, 2250}, {2250, 2500}
> > +};
> > +
> > static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
> > struct cdns_dphy_cfg *cfg,
> > struct phy_configure_opts_mipi_dphy *opts,
> > @@ -360,6 +401,145 @@ static const struct cdns_dphy_info tx_ref_info = {
> > .tx_ops = &tx_ref_dphy_ops,
> > };
> >
> > +static int cdns_dphy_rx_power_on(struct phy *phy)
> > +{
> > + struct cdns_dphy *dphy = phy_get_drvdata(phy);
> > +
> > + /* Start RX state machine. */
> > + writel(DPHY_CMN_SSM_EN | DPHY_CMN_RX_MODE_EN |
> > + FIELD_PREP(DPHY_CMN_RX_BANDGAP_TIMER_MASK,
> > + DPHY_CMN_RX_BANDGAP_TIMER),
> > + dphy->regs + DPHY_CMN_SSM);
> > +
> > + return 0;
> > +}
> > +
> > +static int cdns_dphy_rx_power_off(struct phy *phy)
> > +{
> > + struct cdns_dphy *dphy = phy_get_drvdata(phy);
> > +
> > + writel(0, dphy->regs + DPHY_CMN_SSM);
> > +
> > + return 0;
> > +}
> > +
> > +static int cdns_dphy_rx_get_band_ctrl(unsigned long hs_clk_rate)
> > +{
> > + unsigned int rate, i;
> > +
> > + rate = hs_clk_rate / 1000000UL;
> > + /* Since CSI-2 clock is DDR, the bit rate is twice the clock rate. */
> > + rate *= 2;
> > +
> > + if (rate < bands[0].min_rate)
> > + return -EOPNOTSUPP;
> > +
> > + for (i = 0; i < ARRAY_SIZE(bands); i++) {
> > + if (rate < bands[i].max_rate)
> > + return i;
> > + }
> > +
> > + return -EOPNOTSUPP;
> > +}
> > +
> > +static int cdns_dphy_rx_wait_for_bit(void __iomem *addr, unsigned int bit)
> > +{
> > + u32 val;
> > +
> > + return readl_relaxed_poll_timeout(addr, val, val & BIT(bit), 10,
> > + DPHY_ISO_LANE_READY_TIMEOUT_MS * 1000);
> > +}
> > +
> > +static int cdns_dphy_rx_wait_lane_ready(struct cdns_dphy *dphy,
> > + unsigned int lanes)
> > +{
> > + static const u32 data_lane_ctrl[] = {DPHY_ISO_DL_CTRL_L0,
> > + DPHY_ISO_DL_CTRL_L1,
> > + DPHY_ISO_DL_CTRL_L2,
> > + DPHY_ISO_DL_CTRL_L3};
> > + void __iomem *reg = dphy->regs;
> > + unsigned int i;
> > + int ret;
> > +
> > + /* Data lanes. Minimum one lane is mandatory. */
> > + if (lanes < DPHY_LANES_MIN || lanes > DPHY_LANES_MAX)
> > + return -EINVAL;
> > +
> > + /* Clock lane */
> > + ret = cdns_dphy_rx_wait_for_bit(reg + DPHY_ISO_CL_CTRL_L,
> > + DPHY_ISO_LANE_READY_BIT);
> > + if (ret)
> > + return ret;
> > +
> > + for (i = 0; i < lanes; i++) {
> > + ret = cdns_dphy_rx_wait_for_bit(reg + data_lane_ctrl[i],
> > + DPHY_ISO_LANE_READY_BIT);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int cdns_dphy_rx_configure(struct phy *phy,
> > + union phy_configure_opts *opts)
> > +{
> > + struct cdns_dphy *dphy = phy_get_drvdata(phy);
> > + unsigned int reg;
> > + int band_ctrl, ret;
> > +
> > + band_ctrl = cdns_dphy_rx_get_band_ctrl(opts->mipi_dphy.hs_clk_rate);
> > + if (band_ctrl < 0)
> > + return band_ctrl;
> > +
> > + reg = FIELD_PREP(DPHY_BAND_CFG_LEFT_BAND, band_ctrl) |
> > + FIELD_PREP(DPHY_BAND_CFG_RIGHT_BAND, band_ctrl);
> > + writel(reg, dphy->regs + DPHY_BAND_CFG);
> > +
> > + /*
> > + * Set the required power island phase 2 time. This is mandated by DPHY
> > + * specs.
> > + */
> > + reg = DPHY_POWER_ISLAND_EN_DATA_VAL;
> > + writel(reg, dphy->regs + DPHY_POWER_ISLAND_EN_DATA);
> > + reg = DPHY_POWER_ISLAND_EN_CLK_VAL;
> > + writel(reg, dphy->regs + DPHY_POWER_ISLAND_EN_CLK);
> > +
> > + ret = cdns_dphy_rx_wait_lane_ready(dphy, opts->mipi_dphy.lanes);
> > + if (ret) {
> > + dev_err(dphy->dev, "DPHY wait for lane ready timeout\n");
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int cdns_dphy_rx_validate(struct phy *phy, enum phy_mode mode,
> > + int submode, union phy_configure_opts *opts)
> > +{
> > + int ret;
> > +
> > + if (mode != PHY_MODE_MIPI_DPHY)
> > + return -EINVAL;
> > +
> > + ret = cdns_dphy_rx_get_band_ctrl(opts->mipi_dphy.hs_clk_rate);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return phy_mipi_dphy_config_validate(&opts->mipi_dphy);
> > +}
> > +
> > +static const struct phy_ops rx_ref_phy_ops = {
> > + .power_on = cdns_dphy_rx_power_on,
> > + .power_off = cdns_dphy_rx_power_off,
> > + .configure = cdns_dphy_rx_configure,
> > + .validate = cdns_dphy_rx_validate,
> > +};
> > +
> > +static const struct cdns_dphy_info rx_ref_info = {
> > + .phy_ops = &rx_ref_phy_ops,
> > +};
> > +
> > static int cdns_dphy_probe(struct platform_device *pdev)
> > {
> > struct phy_provider *phy_provider;
> > @@ -417,6 +597,7 @@ static int cdns_dphy_remove(struct platform_device *pdev)
> >
> > static const struct of_device_id cdns_dphy_of_match[] = {
> > { .compatible = "cdns,dphy", .data = &tx_ref_info },
> > + { .compatible = "cdns,dphy-rx", .data = &rx_ref_info },
> > { /* sentinel */ },
> > };
> > MODULE_DEVICE_TABLE(of, cdns_dphy_of_match);
> > @@ -432,5 +613,6 @@ static struct platform_driver cdns_dphy_platform_driver = {
> > module_platform_driver(cdns_dphy_platform_driver);
> >
> > MODULE_AUTHOR("Maxime Ripard <maxime.ripard at bootlin.com>");
> > +MODULE_AUTHOR("Pratyush Yadav <p.yadav at ti.com>");
> > MODULE_DESCRIPTION("Cadence MIPI D-PHY Driver");
> > MODULE_LICENSE("GPL");
> > --
> > 2.33.0
> >
>
> --
> Paul Kocialkowski, Bootlin
> Embedded Linux and kernel engineering
> https://bootlin.com
--
Regards,
Pratyush Yadav
Texas Instruments Inc.
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