On Fr, 2025-09-05 at 12:45 +0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
>
> Add support for module reset handling on the RZ/T2H SoC. Unlike earlier
> CPG/MSSR variants, RZ/T2H uses a unified set of Module Reset Control
> Registers (MRCR) where both reset and deassert actions are done via
> read-modify-write (RMW) to the same register.
>
> Introduce a new MRCR offset table (mrcr_for_rzt2h) for RZ/T2H and assign
> it to reset_regs. For this SoC, the number of resets is based on the
> number of MRCR registers rather than the number of module clocks. Also
> add cpg_mrcr_reset_ops to implement reset, assert, and deassert using RMW
> while holding the spinlock. This follows the RZ/T2H requirements, where
> processing after releasing a module reset must be secured by performing
> seven dummy reads of the same register, and where a module that is reset
> and released again must ensure the target bit in the Module Reset Control
> Register is set to 1.
>
> Update the reset controller registration to select cpg_mrcr_reset_ops for
> RZ/T2H, while keeping the existing cpg_mssr_reset_ops for other SoCs.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> ---
> v2->v3:
> - Simplifed the code by adding a common function cpg_mrcr_set_bit() to handle
> set/clear of bits with options for verify and dummy reads.
> - Added a macro for the number of dummy reads required.
>
> v1->v2:
> - Added cpg_mrcr_reset_ops for RZ/T2H specific handling
> - Updated commit message
> ---
> drivers/clk/renesas/renesas-cpg-mssr.c | 112 ++++++++++++++++++++++++-
> 1 file changed, 108 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c
> index 5ff6ee1f7d4b..81206db2b873 100644
> --- a/drivers/clk/renesas/renesas-cpg-mssr.c
> +++ b/drivers/clk/renesas/renesas-cpg-mssr.c
> @@ -40,6 +40,8 @@
> #define WARN_DEBUG(x) do { } while (0)
> #endif
>
> +#define RZT2H_RESET_REG_READ_COUNT 7
> +
> /*
> * Module Standby and Software Reset register offets.
> *
> @@ -137,6 +139,22 @@ static const u16 srcr_for_gen4[] = {
> 0x2C60, 0x2C64, 0x2C68, 0x2C6C, 0x2C70, 0x2C74,
> };
>
> +static const u16 mrcr_for_rzt2h[] = {
> + 0x240, /* MRCTLA */
> + 0x244, /* Reserved */
> + 0x248, /* Reserved */
> + 0x24C, /* Reserved */
> + 0x250, /* MRCTLE */
> + 0x254, /* Reserved */
> + 0x258, /* Reserved */
> + 0x25C, /* Reserved */
> + 0x260, /* MRCTLI */
> + 0x264, /* Reserved */
> + 0x268, /* Reserved */
> + 0x26C, /* Reserved */
> + 0x270, /* MRCTLM */
> +};
> +
> /*
> * Software Reset Clearing Register offsets
> */
> @@ -736,6 +754,73 @@ static int cpg_mssr_status(struct reset_controller_dev *rcdev,
> return !!(readl(priv->pub.base0 + priv->reset_regs[reg]) & bitmask);
> }
>
> +static int cpg_mrcr_set_bit(struct reset_controller_dev *rcdev, unsigned long id,
> + bool set, bool verify, bool dummy_reads, const char *op_name)
This function is inappropriately named, it does more than just set a
bit.
Why are there three boolean parameters if there are only ever two
combinations of them used? Just have a single bool assert.
Drop the op_name parameter.
> +{
> + struct cpg_mssr_priv *priv = rcdev_to_priv(rcdev);
> + unsigned int reg = id / 32;
> + unsigned int bit = id % 32;
> + u32 bitmask = BIT(bit);
> + void __iomem *reg_addr;
> + unsigned long flags;
> + unsigned int i;
> + u32 val;
> +
> + dev_dbg(priv->dev, "%s %u%02u\n", op_name, reg, bit);
Replace op_name with set ? "assert" : "deassert".
You could later add a str_assert_deassert() helper in string_choices.h.
> +
> + spin_lock_irqsave(&priv->pub.rmw_lock, flags);
> +
> + reg_addr = priv->pub.base0 + priv->reset_regs[reg];
> + /* Read current value and modify */
> + val = readl(reg_addr);
> + if (set)
> + val |= bitmask;
> + else
> + val &= ~bitmask;
> + writel(val, reg_addr);
> +
> + /* Verify the operation if requested */
> + if (verify) {
> + val = readl(reg_addr);
> + if ((set && !(bitmask & val)) || (!set && (bitmask & val))) {
> + dev_err(priv->dev, "Reset register %u%02u operation failed\n", reg, bit);
> + spin_unlock_irqrestore(&priv->pub.rmw_lock, flags);
> + return -EIO;
> + }
> + }
> +
> + /* Perform dummy reads if required */
> + for (i = 0; dummy_reads && i < RZT2H_RESET_REG_READ_COUNT; i++)
> + readl(reg_addr);
Both verify and dummy reads could just live in a single if (!assert) {}
block.
> +
> + spin_unlock_irqrestore(&priv->pub.rmw_lock, flags);
> +
> + return 0;
> +}
> +
> +static int cpg_mrcr_reset(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> + int ret;
> +
> + /* Assert reset */
> + ret = cpg_mrcr_set_bit(rcdev, id, true, true, false, "reset");
> + if (ret)
> + return ret;
No delay necessary for any of the modules that can be reset?
> + /* Deassert reset with dummy reads */
> + return cpg_mrcr_set_bit(rcdev, id, false, false, true, "reset");
Copy & paste error in op_name, but that is fixed if you drop it.
> +}
> +
> +static int cpg_mrcr_assert(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> + return cpg_mrcr_set_bit(rcdev, id, true, true, false, "assert");
> +}
> +
> +static int cpg_mrcr_deassert(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> + return cpg_mrcr_set_bit(rcdev, id, false, false, true, "deassert");
> +}
> +
> static const struct reset_control_ops cpg_mssr_reset_ops = {
> .reset = cpg_mssr_reset,
> .assert = cpg_mssr_assert,
> @@ -743,6 +828,13 @@ static const struct reset_control_ops cpg_mssr_reset_ops = {
> .status = cpg_mssr_status,
> };
>
> +static const struct reset_control_ops cpg_mrcr_reset_ops = {
> + .reset = cpg_mrcr_reset,
> + .assert = cpg_mrcr_assert,
> + .deassert = cpg_mrcr_deassert,
> + .status = cpg_mssr_status,
> +};
> +
> static int cpg_mssr_reset_xlate(struct reset_controller_dev *rcdev,
> const struct of_phandle_args *reset_spec)
> {
> @@ -760,11 +852,23 @@ static int cpg_mssr_reset_xlate(struct reset_controller_dev *rcdev,
>
> static int cpg_mssr_reset_controller_register(struct cpg_mssr_priv *priv)
> {
> - priv->rcdev.ops = &cpg_mssr_reset_ops;
> + /*
> + * RZ/T2H (and family) has the Module Reset Control Registers
> + * which allows control resets of certain modules.
> + * The number of resets is not equal to the number of module clocks.
> + */
> + if (priv->reg_layout == CLK_REG_LAYOUT_RZ_T2H) {
> + priv->rcdev.ops = &cpg_mrcr_reset_ops;
> + priv->rcdev.nr_resets = ARRAY_SIZE(mrcr_for_rzt2h) * 32;
> + } else {
> + priv->rcdev.ops = &cpg_mssr_reset_ops;
> + priv->rcdev.nr_resets = priv->num_mod_clks;
> + }
> +
> priv->rcdev.of_node = priv->dev->of_node;
> priv->rcdev.of_reset_n_cells = 1;
> priv->rcdev.of_xlate = cpg_mssr_reset_xlate;
> - priv->rcdev.nr_resets = priv->num_mod_clks;
> +
> return devm_reset_controller_register(priv->dev, &priv->rcdev);
> }
>
> @@ -1166,6 +1270,7 @@ static int __init cpg_mssr_common_init(struct device *dev,
> priv->control_regs = stbcr;
> } else if (priv->reg_layout == CLK_REG_LAYOUT_RZ_T2H) {
> priv->control_regs = mstpcr_for_rzt2h;
> + priv->reset_regs = mrcr_for_rzt2h;
> } else if (priv->reg_layout == CLK_REG_LAYOUT_RCAR_GEN4) {
> priv->status_regs = mstpsr_for_gen4;
> priv->control_regs = mstpcr_for_gen4;
> @@ -1262,8 +1367,7 @@ static int __init cpg_mssr_probe(struct platform_device *pdev)
> goto reserve_exit;
>
> /* Reset Controller not supported for Standby Control SoCs */
> - if (priv->reg_layout == CLK_REG_LAYOUT_RZ_A ||
> - priv->reg_layout == CLK_REG_LAYOUT_RZ_T2H)
> + if (priv->reg_layout == CLK_REG_LAYOUT_RZ_A)
> goto reserve_exit;
>
> error = cpg_mssr_reset_controller_register(priv);
regards
Philipp
