Re: [PATCH v3 4/7] phy: cdns-dphy: Add Rx support

Vinod Koul
2021-08-06T11:15:48Z

On 25-06-21, 00:11, 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 PHY is in Tx mode by default and it needs to be set in Rx mode by
> setting the submode to PHY_MIPI_DPHY_SUBMODE_RX in the set_mode()
> callback.
>
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
>
> ---
>
> 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 | 174 ++++++++++++++++++++++++++++++++
> 1 file changed, 174 insertions(+)
>
> diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
> index 7d5f7b333893..7534ec957dc5 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/bitops.h>
> +#include <linux/bitfield.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;
> @@ -103,6 +130,22 @@ struct cdns_dphy_driver_data {
> const struct cdns_dphy_ops *rx;
> };
>
> +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. */
> +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}
> +};
> +
> +int num_bands = ARRAY_SIZE(bands);
> +
> static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
> struct cdns_dphy_cfg *cfg,
> struct phy_configure_opts_mipi_dphy *opts,
> @@ -312,6 +355,135 @@ static const struct cdns_dphy_ops tx_ref_dphy_ops = {
> .set_psm_div = cdns_dphy_ref_set_psm_div,
> };
>
> +static int cdns_dphy_rx_power_on(struct cdns_dphy *dphy)
> +{
> + /* 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 cdns_dphy *dphy)
> +{
> + 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;
> + int 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 || rate >= bands[num_bands - 1].max_rate)
> + return -EOPNOTSUPP;
> +
> + for (i = 0; i < num_bands; i++) {
> + if (rate >= bands[i].min_rate && rate < bands[i].max_rate)
> + return i;
> + }
> +
> + /* Unreachable. */
> + WARN(1, "Reached unreachable code.");
> + return -EINVAL;
> +}
> +
> +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);

this looks wrong, val is not initialized, so what/when is condition to
be met..?
--
~Vinod