The PDM (Pulse Density Modulation) hardware block on Qualcomm SoCs contains a GP_MN clock divider that produces a fractional output frequency from a fixed input clock (typically TCXO4): Fout = Fin * (M / N) The hardware encodes the period in the NDIV register as the 1's complement of (N - M), and controls the duty cycle via a separate DUTY register that counts the number of low-phase native clock cycles over the period N. Add a standalone platform driver for this block that uses rational_best_approximation() to find the closest M/N pair within the 9-bit M and 13-bit N hardware limits. Reject ratios which cannot support a valid duty cycle, and program the MDIV, NDIV, and DUTY registers via regmap. Implement determine_rate, set_rate, recalc_rate, get_duty_cycle, and set_duty_cycle operations. The PDM AHB bus clock is gated around every register access. Signed-off-by: Taniya Das --- drivers/clk/qcom/Kconfig | 15 ++ drivers/clk/qcom/Makefile | 1 + drivers/clk/qcom/clk-gp-mnd.c | 333 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 349 insertions(+) diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig index 27d0ab24d50a4ca5587ed8d6085c4d6fcd57eb8c..d9f1df77b715b08a32c164a6d25d88fc545f59cb 100644 --- a/drivers/clk/qcom/Kconfig +++ b/drivers/clk/qcom/Kconfig @@ -2148,4 +2148,19 @@ config SM_VIDEOCC_8450 SM8450 or SM8475 devices. Say Y if you want to support video devices and functionality such as video encode/decode. + +config QCOM_CLK_GP_MND + tristate "Qualcomm PDM GP_MN clock divider" + depends on ARM64 || COMPILE_TEST + help + Support for the Qualcomm PDM GP_MN clock divider found in PDM + (Pulse Density Modulation) hardware blocks. + Given an input clock of frequency Fin (TCXO4), the output + frequency is Fout = Fin * (M / N). For every N input cycles + the divider produces M output cycles. D controls the duty + cycle: it is the number of native clock cycles in which the + GP_MN output is low, counted over 8192 native clock cycles. + + Say Y or M if you want to support GP_MN-based frequency and + duty-cycle configuration on Qualcomm SoCs. endif diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile index 6affb5073f269d18f1b78d6c7f92e14baeade1e5..4e8563be8e1b99aef48b227ff0c5dc04dc092d0a 100644 --- a/drivers/clk/qcom/Makefile +++ b/drivers/clk/qcom/Makefile @@ -227,6 +227,7 @@ obj-$(CONFIG_SM_VIDEOCC_8550) += videocc-sm8550.o obj-$(CONFIG_SM_VIDEOCC_8750) += videocc-sm8750.o obj-$(CONFIG_SM_VIDEOCC_MILOS) += videocc-milos.o obj-$(CONFIG_SPMI_PMIC_CLKDIV) += clk-spmi-pmic-div.o +obj-$(CONFIG_QCOM_CLK_GP_MND) += clk-gp-mnd.o obj-$(CONFIG_KPSS_XCC) += kpss-xcc.o obj-$(CONFIG_QCOM_HFPLL) += hfpll.o obj-$(CONFIG_KRAITCC) += krait-cc.o diff --git a/drivers/clk/qcom/clk-gp-mnd.c b/drivers/clk/qcom/clk-gp-mnd.c new file mode 100644 index 0000000000000000000000000000000000000000..818726c02b615689928cf09b4b34f0889d4246d8 --- /dev/null +++ b/drivers/clk/qcom/clk-gp-mnd.c @@ -0,0 +1,333 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * PDM GP_MND clock divider register offsets. + * + * The hardware computes: + * Fout = Fin * (M / N) + * + * with duty cycle controlled by D, where M < D < (N - M). + * + * Register encoding: + * MDIV = M + * NDIV = ~(N - M) [1's complement of (N - M), masked to N_REG_WIDTH bits] + * DUTY = D + */ +#define GP_MND_MDIV_REG 0x0 +#define GP_MND_NDIV_REG 0x4 +#define GP_MND_DUTY_REG 0x8 + +#define GP_MND_M_WIDTH 9 +#define GP_MND_N_WIDTH 13 + +#define GP_MND_MAX_M GENMASK(GP_MND_M_WIDTH - 1, 0) +#define GP_MND_MAX_N GENMASK(GP_MND_N_WIDTH - 1, 0) + +/** + * struct clk_gp_mnd - GP_MND fractional clock divider + * @dev: device for runtime PM + * @regmap: register map for the PDM block + * @hw: handle between common and hardware-specific interfaces + * @m_val: M value (numerator) + * @n_val: N value (period) + */ +struct clk_gp_mnd { + struct device *dev; + struct regmap *regmap; + struct clk_hw hw; + unsigned int m_val; + unsigned int n_val; +}; + +#define to_clk_gp_mnd(_hw) container_of(_hw, struct clk_gp_mnd, hw) + +static int gp_mnd_clk_runtime_resume(struct clk_gp_mnd *gp) +{ + return pm_runtime_resume_and_get(gp->dev); +} + +static void gp_mnd_clk_runtime_put(struct clk_gp_mnd *gp) +{ + pm_runtime_put(gp->dev); +} + +static int gp_mnd_clk_determine_rate(struct clk_hw *hw, + struct clk_rate_request *req) +{ + unsigned long m = 0, n = 0; + + rational_best_approximation(req->rate, req->best_parent_rate, + (unsigned long)GP_MND_MAX_M, + (unsigned long)GP_MND_MAX_N, + &m, &n); + if (!m || !n) + return -EINVAL; + + if (n <= 2 * m + 1) + return -EINVAL; + + req->rate = DIV_ROUND_CLOSEST_ULL((u64)req->best_parent_rate * m, n); + + return 0; +} + +static int gp_mnd_clk_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_gp_mnd *gp = to_clk_gp_mnd(hw); + unsigned long m = 0, n = 0; + unsigned int d_val, n_val; + int ret; + + rational_best_approximation(rate, parent_rate, + (unsigned long)GP_MND_MAX_M, + (unsigned long)GP_MND_MAX_N, + &m, &n); + if (!m || !n) + return -EINVAL; + + if (n <= 2 * m + 1) + return -EINVAL; + + ret = gp_mnd_clk_runtime_resume(gp); + if (ret) + return ret; + + ret = regmap_write(gp->regmap, GP_MND_MDIV_REG, m); + if (ret) + goto err_runtime_put; + + /* N divider holds the 1's complement of (N - M), N_WIDTH bits wide */ + n_val = ~(n - m) & GP_MND_MAX_N; + ret = regmap_write(gp->regmap, GP_MND_NDIV_REG, n_val); + if (ret) + goto err_runtime_put; + + /* Program the closest-to-50% duty cycle. */ + d_val = n / 2; + ret = regmap_write(gp->regmap, GP_MND_DUTY_REG, d_val); + if (ret) + goto err_runtime_put; + + gp->m_val = m; + gp->n_val = n; + +err_runtime_put: + gp_mnd_clk_runtime_put(gp); + + return ret; +} + +static unsigned long gp_mnd_clk_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_gp_mnd *gp = to_clk_gp_mnd(hw); + unsigned int m_val, n_val; + int ret; + + ret = gp_mnd_clk_runtime_resume(gp); + if (ret) + return 0; + + ret = regmap_read(gp->regmap, GP_MND_MDIV_REG, &m_val); + if (ret) + goto out_runtime_put; + + m_val &= GP_MND_MAX_M; + + ret = regmap_read(gp->regmap, GP_MND_NDIV_REG, &n_val); + if (ret) + goto out_runtime_put; + + /* Reverse the 1's complement encoding: N = ~NDIV_REG + M */ + n_val = (~n_val & GP_MND_MAX_N) + m_val; + +out_runtime_put: + gp_mnd_clk_runtime_put(gp); + + if (ret) + return 0; + + if (!n_val) + return 0; + + gp->m_val = m_val; + gp->n_val = n_val; + + return DIV_ROUND_CLOSEST_ULL((u64)parent_rate * m_val, n_val); +} + +static int gp_mnd_clk_get_duty_cycle(struct clk_hw *hw, struct clk_duty *duty) +{ + struct clk_gp_mnd *gp = to_clk_gp_mnd(hw); + unsigned int d_val; + int ret; + + if (!gp->n_val) { + duty->num = 1; + duty->den = 2; + return 0; + } + + ret = gp_mnd_clk_runtime_resume(gp); + if (ret) + return ret; + + ret = regmap_read(gp->regmap, GP_MND_DUTY_REG, &d_val); + + gp_mnd_clk_runtime_put(gp); + + if (ret) + return ret; + + if (d_val >= gp->n_val) + return -EINVAL; + + /* DUTY stores the low-phase count; report the high-phase duty cycle. */ + duty->num = gp->n_val - d_val; + duty->den = gp->n_val; + + return 0; +} + +static int gp_mnd_clk_set_duty_cycle(struct clk_hw *hw, struct clk_duty *duty) +{ + struct clk_gp_mnd *gp = to_clk_gp_mnd(hw); + unsigned int d_val; + int ret; + + if (!gp->n_val || !gp->m_val || !duty->den || duty->num > duty->den) + return -EINVAL; + + /* D = (1 - duty) * N, giving the low-phase count */ + d_val = DIV_ROUND_UP((u64)(duty->den - duty->num) * gp->n_val, duty->den); + + /* Hardware constraint: M < D < (N - M) */ + if (d_val <= gp->m_val || d_val >= (gp->n_val - gp->m_val)) + return -EINVAL; + + ret = gp_mnd_clk_runtime_resume(gp); + if (ret) + return ret; + + ret = regmap_write(gp->regmap, GP_MND_DUTY_REG, d_val); + + gp_mnd_clk_runtime_put(gp); + + return ret; +} + +static const struct clk_ops clk_gp_mnd_ops = { + .determine_rate = gp_mnd_clk_determine_rate, + .set_rate = gp_mnd_clk_set_rate, + .recalc_rate = gp_mnd_clk_recalc_rate, + .get_duty_cycle = gp_mnd_clk_get_duty_cycle, + .set_duty_cycle = gp_mnd_clk_set_duty_cycle, +}; + +static const struct regmap_config gp_mnd_regmap_config = { + .reg_bits = 32, + .reg_stride = 4, + .val_bits = 32, + .fast_io = true, +}; + +static int clk_gp_mnd_probe(struct platform_device *pdev) +{ + struct clk_parent_data parent_data = { .index = 0 }; + struct clk_init_data init = { + .name = "gp_mn_clk", + .ops = &clk_gp_mnd_ops, + .parent_data = &parent_data, + .num_parents = 1, + .flags = CLK_GET_RATE_NOCACHE, + }; + struct device *dev = &pdev->dev; + struct clk_gp_mnd *gp; + struct clk *clk; + void __iomem *base; + int ret; + + gp = devm_kzalloc(dev, sizeof(*gp), GFP_KERNEL); + if (!gp) + return -ENOMEM; + + gp->dev = dev; + + ret = devm_pm_runtime_enable(dev); + if (ret) + return ret; + + ret = devm_pm_clk_create(dev); + if (ret) + return ret; + + ret = pm_clk_add(dev, "ahb_clk"); + if (ret) + return dev_err_probe(dev, ret, "failed to get ahb_clk\n"); + + clk = devm_clk_get(dev, "pdm_clk"); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + /* Set default rate if not already configured */ + if (!clk_get_rate(clk)) { + ret = clk_set_rate(clk, 19200000); + if (ret) + dev_warn(dev, "failed to set default pdm_clk rate\n"); + } + + base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(base)) + return dev_err_probe(dev, PTR_ERR(base), + "failed to map PDM registers\n"); + + gp->regmap = devm_regmap_init_mmio(dev, base, &gp_mnd_regmap_config); + if (IS_ERR(gp->regmap)) + return dev_err_probe(dev, PTR_ERR(gp->regmap), + "failed to init regmap\n"); + + gp->hw.init = &init; + + ret = devm_clk_hw_register(dev, &gp->hw); + if (ret) + return dev_err_probe(dev, ret, + "failed to register gp_mnd clock\n"); + + return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, &gp->hw); +} + +static const struct of_device_id clk_gp_mnd_match_table[] = { + { .compatible = "qcom,sc7280-gp-mnd" }, + { } +}; +MODULE_DEVICE_TABLE(of, clk_gp_mnd_match_table); + +static const struct dev_pm_ops clk_gp_mnd_pm_ops = { + SET_RUNTIME_PM_OPS(pm_clk_suspend, pm_clk_resume, NULL) +}; + +static struct platform_driver clk_gp_mnd_driver = { + .probe = clk_gp_mnd_probe, + .driver = { + .name = "qcom-clk-gp-mnd", + .of_match_table = clk_gp_mnd_match_table, + .pm = pm_ptr(&clk_gp_mnd_pm_ops), + }, +}; +module_platform_driver(clk_gp_mnd_driver); + +MODULE_DESCRIPTION("Qualcomm PDM GP_MND clock divider driver"); +MODULE_LICENSE("GPL"); -- 2.34.1