Hi Randy, Thanks a lot for the review.
> -----Original Message----- > From: Randy Dunlap [mailto:rdun...@infradead.org] > Sent: Saturday, December 16, 2017 2:18 PM > To: Dhaval Rajeshbhai Shah <ds...@xilinx.com>; a...@arndb.de; > gre...@linuxfoundation.org; robh...@kernel.org; mark.rutl...@arm.com > Cc: devicet...@vger.kernel.org; linux-kernel@vger.kernel.org; > michal.si...@xilinx.com; Hyun Kwon <hy...@xilinx.com>; Dhaval Rajeshbhai > Shah <ds...@xilinx.com> > Subject: Re: [PATCH v4 2/2] misc: xlnx_vcu: Add Xilinx ZYNQMP VCU logicoreIP > init driver > > On 12/14/2017 11:24 PM, Dhaval Shah wrote: > > Xilinx ZYNQMP logicoreIP Init driver is based on the new LogiCoreIP > > design created. This driver provides the processing system and > > programmable logic isolation. Set the frequency based on the clock > > information get from the logicoreIP register set. > > > > It is put in drivers/misc as there is no subsystem for this logicoreIP. > > > > Signed-off-by: Dhaval Shah <ds...@xilinx.com> > > --- > > > > drivers/misc/Kconfig | 15 ++ > > drivers/misc/Makefile | 1 + > > drivers/misc/xlnx_vcu.c | 631 > > ++++++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 647 insertions(+) > > create mode 100644 drivers/misc/xlnx_vcu.c > > > diff --git a/drivers/misc/xlnx_vcu.c b/drivers/misc/xlnx_vcu.c new > > file mode 100644 index 0000000..f489d34 > > --- /dev/null > > +++ b/drivers/misc/xlnx_vcu.c > > @@ -0,0 +1,631 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Xilinx VCU Init > > + * > > + * Copyright (C) 2016 - 2017 Xilinx, Inc. > > + * > > + * Contacts Dhaval Shah <ds...@xilinx.com> > > + */ > > +#include <linux/clk.h> > > +#include <linux/device.h> > > +#include <linux/errno.h> > > +#include <linux/io.h> > > +#include <linux/module.h> > > +#include <linux/of_platform.h> > > +#include <linux/platform_device.h> > > [snip] > > > > +/** > > + * xvcu_set_vcu_pll_info - Set the VCU PLL info > > + * @xvcu: Pointer to the xvcu_device structure > > + * > > + * Programming the VCU PLL based on the user configuration > > + * (ref clock freq, core clock freq, mcu clock freq). > > + * Core clock frequency has higher priority than mcu clock frequency > > + * Errors in following cases > > + * - When mcu or clock clock get from logicoreIP is 0 > > + * - When VCU PLL DIV related bits value other than 1 > > + * - When proper data not found for given data > > + * - When sis570_1 clocksource related operation failed > > + * > > + * Return: Returns status, either success or error+reason > > + */ > > +static int xvcu_set_vcu_pll_info(struct xvcu_device *xvcu) { > > + u32 refclk, coreclk, mcuclk, inte, deci; > > + u32 divisor_mcu, divisor_core, fvco; > > + u32 clkoutdiv, vcu_pll_ctrl, pll_clk; > > + u32 cfg_val, mod, ctrl; > > + int ret; > > + unsigned int i; > > + const struct xvcu_pll_cfg *found = NULL; > > + > > + inte = xvcu_read(xvcu->logicore_reg_ba, VCU_PLL_CLK); > > + deci = xvcu_read(xvcu->logicore_reg_ba, VCU_PLL_CLK_DEC); > > + coreclk = xvcu_read(xvcu->logicore_reg_ba, VCU_CORE_CLK) * MHZ; > > + mcuclk = xvcu_read(xvcu->logicore_reg_ba, VCU_MCU_CLK) * MHZ; > > + if (!mcuclk || !coreclk) { > > + dev_err(xvcu->dev, "Invalid mcu and core clock data\n"); > > + return -EINVAL; > > + } > > + > > + refclk = (inte * MHZ) + (deci * (MHZ / FRAC)); > > + dev_dbg(xvcu->dev, "Ref clock from logicoreIP is %uHz\n", refclk); > > + dev_dbg(xvcu->dev, "Core clock from logicoreIP is %uHz\n", coreclk); > > + dev_dbg(xvcu->dev, "Mcu clock from logicoreIP is %uHz\n", mcuclk); > > + > > + clk_disable_unprepare(xvcu->pll_ref); > > + ret = clk_set_rate(xvcu->pll_ref, refclk); > > + if (ret) > > + dev_warn(xvcu->dev, "failed to set logicoreIP refclk rate\n"); > > + > > + ret = clk_prepare_enable(xvcu->pll_ref); > > + if (ret) { > > + dev_err(xvcu->dev, "failed to enable pll_ref clock source\n"); > > + return ret; > > + } > > + > > + refclk = clk_get_rate(xvcu->pll_ref); > > + > > + /* > > + * The divide-by-2 should be always enabled (==1) > > + * to meet the timing in the design. > > + * Otherwise, it's an error > > + */ > > + vcu_pll_ctrl = xvcu_read(xvcu->vcu_slcr_ba, VCU_PLL_CTRL); > > + clkoutdiv = vcu_pll_ctrl >> VCU_PLL_CTRL_CLKOUTDIV_SHIFT; > > + clkoutdiv = clkoutdiv && VCU_PLL_CTRL_CLKOUTDIV_MASK; > > + if (clkoutdiv != 1) { > > + dev_err(xvcu->dev, "clkoutdiv value is invalid\n"); > > + return -EINVAL; > > + } > > + > > + for (i = ARRAY_SIZE(xvcu_pll_cfg) - 1; i > 0; i--) { > > When does that for loop terminate? > This loop will terminate either it reach to i =0 and one other case is when it find the proper expected value. Break statement is used to exit in that case. > > + const struct xvcu_pll_cfg *cfg = &xvcu_pll_cfg[i]; > > + > > + fvco = cfg->fbdiv * refclk; > > + if (fvco >= FVCO_MIN && fvco <= FVCO_MAX) { > > + pll_clk = fvco / VCU_PLL_DIV2; > > + if (fvco % VCU_PLL_DIV2 != 0) > > + pll_clk++; > > + mod = pll_clk % coreclk; > > + if (mod < LIMIT) { > > + divisor_core = pll_clk / coreclk; > > + } else if (coreclk - mod < LIMIT) { > > + divisor_core = pll_clk / coreclk; > > + divisor_core++; > > + } else { > > + continue; > > + } > > + if (divisor_core >= DIVISOR_MIN && > > + divisor_core <= DIVISOR_MAX) { > > + found = cfg; > > + divisor_mcu = pll_clk / mcuclk; > > + mod = pll_clk % mcuclk; > > + if (mcuclk - mod < LIMIT) > > + divisor_mcu++; > > + break; This is the break statement to exit when proper value is find. > > + } > > + } > > + } > > + > > + if (!found) { > > + dev_err(xvcu->dev, "Invalid clock combination.\n"); > > + return -EINVAL; > > + } > > [snip] > > -- > ~Randy
